Officially, Arthur was the Fourth Main Antagonist, and one of the most dangerous, in the series. He was the only antagonist to have successfully killed for three decades, while remaining hidden in a perfect cover life. He was thought by the FBI to be a mere "myth" chased by Special Agent Frank Lundy.
Trinity's pattern was to carry out a kill cycle roughly once a year (occasionally twice, or skipping a year). After the discovery of Arthur's killings by Special Agent Frank Lundy, he was dubbed Trinity or The Trinity Killer, due to the initial thought that each kill cycle involved three murder rituals.
During the past fifteen years, Lundy had counted 15 kill cycles. When Lisa Bell was murdered, Lundy learned of an additional fifteen years, dating back to Vicky Noonan (likely with a similar number of cycles). It was also discovered by Dexter Morgan that it was four murders per cycle, not three. The 'missing' ritual involved the live burial of a 10-year-old boy at the beginning of each cycle.
Trinity has been polled by many viewers of DEXTER as the ultimate antagonist in the series, despite his objectionable methods of murder. His popularity might be due to actor John Lithgow's superb portrayal of the killer, which earned him a Golden Globe award and an Emmy award.
Arthur masqueraded as a Church-going family man that was adored as a beloved teacher, husband, father, and model citizen who helped the community through an organization known as Four Walls One Heart, which built homes for the homeless. To the general public, he had survived this way for decades, perfectly hiding his true face while using the traveling nature of Four Walls One Heart in order to confirm where he would start his next cycle of four victims, before returning home for a "cool-down" period.
Uniquely, among many of the serial killers that Dexter had faced, Mitchell (at least initially) did not kill outside of his well-established cycle, and generally posed no threat to anyone around him once the cycle was completed (There were exceptions to this in terms of his family members, whom he terrorized at times.) Despite his M.O being almost untraceable, the very nature of his kill cycle, and his near-perfect cover life, Arthur's personality was so diversely split that he could not improvise if something did not go according to his plan, and it was his greatest weakness.
After Arthur realized that Dexter was hunting him, he began to recognized that Dexter, like him, was fumbling with his camouflage. This seemed to instill within him mental confidence and stability, allowing him to adapt more carefully to changing circumstances. Unfortunately for Arthur, this did him little good, as Dexter soon captured and killed him. Arthur's final kill, though, did strike a devastating blow to Dexter - his wife, Rita. Just before his death, Arthur seemed to accept that, in the end, his rampage was justly halted. He predicted that, eventually, the same would happen to Dexter, as he knew that he had destroyed his family life and his means of keeping his humanity...
Before Arthur died, he was a man in his early 60's with white-gray thinning hair, blue eyes, as well as an imposing height and build. In spite of his age, Arthur possessed a considerable amount of strength, which was seen when he subdued a strong individual like Dexter in a choke hold and overpowered his athletic and muscular son, Jonah, with startling ease.
When on the job (at the dig sites), he preferred a T-shirt and blue jeans, as well as work boots and equipment used for the dig. When teaching at school, he wore much more formal attire befitting his occupation as a teacher. This formal attire was also seen when he went to church. This could include tan colored or grey suits that remained unbuttoned. He also frequently wore mirrored sunglasses.
On the night that he kidnapped Tarla Grant, he wore dark clothing. When he bludgeoned Earl Doorman, he wore a blue jumpsuit, along with a face shield and plastic gloves, to prevent the blood from spraying onto him.
Being 'born in blood' - Dexter Morgan's euphemism for psychological trauma leading to homicidal impulses - coupled with Mitchell's longevity as a killer made this man's personality incredibly complex, comprising of various personas and moods which seemed to switch at random. Possibly due to his age - thus his increasing lack of humanity - the boundaries compartmentalizing his life were starting to crumble. As quoted by Dexter himself, "Yesterday he was jumping down my throat - today he is a happy dancing man....Is that mask of his crumbling??".
The Family Man
Dexter: "A wolf in sheep's clothing. Hour by hour the spitting image of a normal man. Up at 6 AM. Breakfast 7 at AM. Work - 8:30. A study session shaping young minds...even on a Saturday. Noon lunch with Faculty, out at 3:00. Dinner at 6:00. Father, husband, teacher, Deacon...all in the name of blending in. Camouflage is nature's craftiest trick."
Arthur's personality was known to be very baffling, even to Dexter. Mitchell's public personality was that of a kind older gentleman that was a loving father and husband. He was an active member of the community, who built houses for the homeless in his spare time. In his daily life, he went to church and sung as a preacher, and he then spent his daytimes at work as a school teacher with the perfect zeal for guiding youth and helping them grow. It was also his role as a school teacher which resulted in his extra-curricular 'activities' having to take place within school holidays. Despite his abusive nature towards his children and his wife, Dexter noted from his many days of observation that, at least some of Arthur's love and affection for his family members, is genuine; he was also shown to have affectionate, everyday conversation with his wife, Sally, though this took place outside of Dexter's vision.
An extension of his monster escaping into his personal life, the abuser was a violent part of Arthur that Dexter did not want to have. However, Arthur seemed to have lost control of his Dark Passenger, which lead to occasional appearances of it in the presence of his family that came in the form of violent outbursts and tirades.
Underneath Arthur's fake personality, however, is a violent monster that constantly kept his family (the Mitchell family, not Christine) caged within his personal life. For his wife, she had to do everything he demanded and, fearing that something might happen to her or her children...she'd obey him almost as if she was under mind control (her fear was so great that she could never think of doing anything else). For his daughter, Rebecca Mitchell, he kept her locked up within the house and especially at night with bolts and padlocks to insure that she is kept "in" and, in a way, keep those that might do something to her "out". Jonah Mitchell is practically a reflection of Arthur's abusive father taking out his frustrations and anger on his son. Arthur, having grown up in this environment, had it in turn effect him to the degree that he could not control his anger and would enter a mode of rage whenever Jonah irritated him. Arthur had been known to hit Jonah, choke him, even break his pinky...and completely throw out anything of praise for his son as if it didn't matter to himself in the slightest. However, at the same time, he was also capable of treating his family nicely behind closed doors as well, and it is possible that he may have shared the genuine love for them that they had for him, despite his abusive ways. It was usually only when Jonah angered him that he switched behaviors and they saw the monster within him.
When it came to his other daughter, Christine Hill, he treated her in two fashions. When he was happy with her, he'd act like a caring father to a daughter like a "Daddy's Girl" relationship. He'd smile at her, call her beautiful and everything that a daughter would want from her father...However, whenever he was frustrated with her, he'd call her names behind her back and completely shut her out of his life. After hearing about the news of her death, he entered a deep sorrow. However, before Arthur's death at the hands of Dexter, he pushed the emotion out of Arthur that forced him to throw her out as "weak", thus illustrating BOTH sides of his relationship with her...
Sorrowful Lone Boy
With his original family long gone in a tragic past, Arthur would often reminisce about his sister, mother, and father. In the memory of his sister, he spent a lot of time with her treasured ashes, even spreading them at his own kill sites. He was very protective of his sister's ashes and, when the pot that has them in it was destroyed, he fell into an immense fit of rage. Before he bludgeoned a victim he would share a drink with his father, with an empty chair across from him. His ongoing relationship with his father was the most dramatic. Arthur willed himself to go to a local bar just to have himself beaten senseless, while yelling insults at his attacker. This most likely represented the abuse that his own father placed on him...and, in turn, the abuse that Arthur delivered to Jonah. For his mother, he'd lamented the loss of her at such an early age, and would briefly grieve after he killed the third person in the cycle.
The ChildThe first personality in the child of the killings, Arthur approached any given young boy at the age of 10 and typically introduced himself as a police officer. When adopting this fake personality, he pulled it off generally well (including a fake badge) and made it appear that the child's parents were in a wreck or some other type of disaster. It's then that he lured them off to his van to abduct them and bring them to a safe place (near a dig site that he'll leave them to die in). For a few days, he would play trains with the children or at least attempt to, constantly calling them by his own name as if he was a child again speaking with himself. He acted very innocent in this light, never once harming the child during this stay and always suggested that they wear a similar set of PJs that he once wore.
Typically, the boy eventually admitted that he can be called Arthur, Arthur told him that it's time for them to be set free and he'd drug some ice cream to put them to sleep for a little while. He'd then move the boy to the dig site, filled with cement and would bury them alive when they're senseless, thus dying a painless, unknowing death, in the very same way that his own innocence was lost.
Arthur became very defensive whenever he was called a pedophile, most likely because he, in a way, viewed a child as a manifestation of the innocence that he once had and he couldn't bear to think of some one hurting them (even though he did it himself).
The Caring BrotherThe second personality for a young woman in the killings, Arthur stalked young women between the ages of 16 and about 24, until he decided he's ready to make his move on them. He'd break into her house, calmly stalking her into the bathroom when she is ready to take a bath or a shower. He would subdue her and strip her naked, along with himself, moving both of them to the tub and possibly forcing the girl into a sleeper hold to use a razor blade to slit their thigh and force them to bleed out. In the process, he'd pull a mirror out to let her look into it while she dies, thus signifying the way his sister looked at him after discovering him watching her shower years before. After he finished, he'd leave bit traces of ash (left over by his sister) at the crime scene.
Later on, Arthur would take a shower hot enough to burn himself, most likely to wash off the innocence that he lost...or some other mixed emotion.
The Forgotten SonThe third personality for a middle-aged woman with two children in the killings, Arthur would find a woman matching the age of his mother that is the parent of two others, much like himself and his own sister. He would first meet up with the woman and pretended to be a kind old gentleman either walking a dog or some other mundane task, just so that he could introduce himself to them and learn a little about them. Here he adopted the simple personality that just about anyone can fake - common courtesy and small talk. Afterwards, he'd drop the act and find a way to get her alone, threatening her as he makes her drive to a tall abandoned building. From here it's all based on his orders and her voluntary choice, that is, unless she refuses to comply. As the two of them reach the spot where she's supposed to jump from (just like his mother did), he'd urge her to fall back based on her own will. If the woman did not want to, he'd start to tell her that he'd make her children suffer if she does not follow his orders, to which she'd eventually let herself fall and die. Arthur would then leave traces of ash here, after feeling an immense flood of emotions hit him.
Father Vs. Son
The fourth personality for an older man with possibly two children in the killings, Arthur would locate a father matching the age of his own father. Because not every one of his victims was a drunkard, he'd need to find someone else to take half of the ritual in this kill by taking out their drunken fury on Arthur with multiple punches and kicks while he insults them (much like his own father would do to him back in his past). After that was finished, he'd start stalking another man to an area and start yelling insults at them as he bludgeoned them with some type of weapon (after a recommendation from a local store owner, it becomes a hammer). During this entire process, he could be portrayed as a very vulnerable man fighting back against his father, despite the fact that his victim was the one on the defense in this situation. Once again, Arthur would leave trace evidence of ash after he's finished killing the man and would start to sink back into reality.
The True Arthur
Arthur always had a hard time accepting who he truly was and, when he was faced with the option to kill something (such as a deer), he began to cower, as if he had never picked up a weapon before. This could have suggested a slight crack in the already unstable persona he lived with, further proving that he never really took pride in his killings. It is more than possible that, by doing what he did, Arthur attained a specific recollection of the events of his childhood and was simply trying to prove how 'innocent' he was, even in such an indirect and sinful manner.
Arthur, in all reality, disliked the demon within himself and had lost control of his life because of it - So much so that he'd been contemplating ways to stop it, to kill the demon...in killing himself. Little to Dexter's knowledge, Arthur had been building his own coffin as of late and wished to end his own life in order to stop the monster...thus a planned trip was made to a dig site where he could jump to his death much like his mother. After finding out more from Dexter, he learns that he killed a man (though Arthur believes it to be accidental) and thus begun sharing his past...to relay to someone finally about who he truly was from the past, though did not reveal to Dexter personally that he kills people.Arthur changed drastically at this point, becoming almost ecstatic about his newfound "friend" and went overboard by becoming too open to try and make families listen to him while meeting plenty of people. In a way, it could be that Dexter was officially Arthur's way of confessing to his sins without actually saying them and he was happy to be free of them, ready to take his own life. Later on, as Dexter prepares a kill room and attempts to nab Arthur in his room, he finds him missing and so goes to the Four Walls Build to find him. Unbeknownst to him, Arthur was planning to kill himself all along and relieve himself of the demon inside him. Ironically, Arthur's suicide plan prevented his death at the hands of Dexter, as Dexter noticed him trying to jump off of a building and purposely saved his life, just so that he can have him on his own table. Arthur then begun to act as if new life has been breathed into him and praised Dexter, having believed that God saved his life. However, it was soon revealed that Arthur had returned to his previous personality, no longer wanting to end his own life, but continue in his bloodthirsty ways...
The true Arthur only appeared when Dexter (first playing as Kyle Butler) found out just how far Arthur would go in his acts of violence. After a mishap involving Dexter almost killing Arthur in his own home, Arthur forced his next cycle to begin early...thus kidnapping a child for his next kill. During this time, the two played cat and mouse, with Dexter trying to find Arthur, while the latter was dangling the boy's life at the end of a thread without revealing anything about his process. When Dexter finally figured it out, as well as the location of where the boy would die, the two confront one another, but Arthur manages to escape...from here on moving onto the hunt.
When on the hunt for who Dexter really is, he was shown to be a cold and calculating man that would use bait to find out what he needs. He did, however, talk in a more relaxed, almost cheery voice as if he was enjoying this game. In due time, he finally figured out where Dexter works and met him face to face in the Homicide department...a true stareoff occurring between the two. After a threat here and there, Dexter tailed him to a garage and attempted to set him up for his own Ritual. However, he ended up failing when caught up in an ordeal with some sheriffs. When Dexter returned to the van where he left an unconscious Arthur, he found nothing but an empty space where he once was.
Arthur took pride in the vehicle that he possessed, becoming highly infuriated with Jonah for damaging it beforehand. After taking the windshield clean off, he got it fixed and painted up nicely. Of course, during this time, he acted out his revenge on Dexter for not only stopping his cycle, but also attempting to kill him earlier. In a break of the cycle that was technically still a part of the normal order (even though the boy survived, he moved on to the woman in the bathtub, though he chose to combine that kill with the third kill of an older woman with two children), he goes to Rita's house and sets her up for a kill just like his second in order...slashing her thigh and allowing her to bleed out within a bathtub. This proves that, in a fit of rage with his passenger, he needed to leave something behind to show Dexter punishment after his attempted escape from Miami.After killing Rita and feeling accomplished, Arthur picked up his vehicle and drove off with a smile on his face...truly feeling like he was getting away with murder for the very first time, rather than just trying to please his Dark Passenger that always called to him. However, Dexter had secretly sabotaged his car, removed the oil cap and hid in his trunk, in order to capture and kill him. It is here that Arthur expressed everything that is true about him. He says that he never took pride in his killings (unlike Dexter), but only had to because he couldn't control his urges. He craved to be free of them, to be stopped without trying...and then lamented that his plan to be stopped by praying for it to happen finally worked because Dexter arrived and finally did exactly that. Arthur began to show remorse for his murders and only wishes to be set free of his Dark Passenger, as he accepts God's will in all of this. He then went on to say that it's already over, and Dexter is baffled, as he couldn't understand what Arthur meant by that statement. He concluded that Arthur had to be referring to his killing spree, basically accepting his own death, but it is likely that he was actually referring to Dexter's desire and ambition to become a good family man, but what Dexter didn't know was that this goal was already prevented by the death of Rita. Arthur then noticed his train set and record player, asking in his final moments if he could hear his train and music play before he gets killed, which suggested a return to his innocence once more and a hope to die peacefully.
Arthur Mitchell was born in Tampa Bay, Florida and lived in a two story blue house for most of his young life. He grew up just like any other boy would, that is until one day in 1959 when he became curious of his sister while she was taking a shower and he stood in the doorway, watching her through the mirror. When his sister noticed him, she suddenly freaked and slipped, breaking the glass on the shower door which forced a shard to slash her leg open and make her bleed out there in front of him. This graphic scene of violence scarred Arthur emotionally forever and came as a hard blow to the family as a whole. For a year after the incident, his mother, Marsha, grew increasingly depressed, culminating in her suicide by jumping off of a bridge in 1960. His father, Henry, became a drinker and was physically abusive to Arthur, blaming him for the deaths of Vera and Marsha; frequently calling him a pervert who killed them. In 1964, Henry was found bludgeoned to death in an alley (it is presumed that Arthur himself, who would have been 14 or 15 at the time, was the killer). However, the emotional and physical abuse that Arthur suffered at the hands of his family furthered his path down the wrong way of accepting his passenger.
Arthur would continue to grow up, eventually entering college It is possible he went to Schaffer High School (the same high school his sister attended during her high school career) along the way. What happened to him after his father's death is not revealed. It's possible that he had some other relatives who took him in, or that he was somehow emancipated. After graduating college with a teaching degree, he'd later become a teacher here in his hometown and would meet Christine Hill's mother, Lorraine Hill, later conceiving his first daughter. Arthur would eventually enter the organization known as Four Walls, One Heart and would use this as his alibi when starting his kill cycles. One night his daughter Christine actually witnessed the death of one of Arthur's victims, some 30 years before (the one in the same house that was featured in the first episode of the fourth season) though she never said anything about it out of the love for her father. Arthur would go on multiple trips, sending home multiple postcards saying "Wish you were here. Love, Daddy". Arthur's relationship with Lorraine ended (he would later tell Dexter that it was because of his habit of pushing people away because of his past) and he and Christine became estranged, only meeting around holidays and her birthday.
At some point in time, FBI Agent Frank Lundy would catch onto the pattern of what he began to dub the "Trinity Killer", though Arthur was most likely ignorant to the knowledge that someone had figured out his pattern and finally connected each killing. Lundy would effectively chase a "ghost" all the way across the country without ever figuring out who he was until it was too late.
Some 20 years before the current storyline, Arthur would meet his future wife Sally Mitchell and conceive two children, Jonah Mitchell and Becca Mitchell. He would continue to raise this family as well as stay on as a longterm teacher with a local high school while committing to various other activities. His newfound family life also estranged him even further from Christine, of whose existence they presumably remained unaware. Behind closed doors he would keep his daughter imprisoned and abuse his son and wife when he was in terrible moods and then treat them nicely when he was in a good mood. When his time for another cycle began, he would go to a dig with the Four Walls organization and kill a boy before the dig actually started, along with the three other victims.
Arthur Mitchell was a middle-aged serial killer who has been active for three decades without being noticed. Agent Frank Lundy , the FBI's lead investigator of his crimes, has dubbed him "The Trinity Killer" because it was believed that he killed in threes. However it has since come to light that he in actuality kills four victims every cycle (Lost Boys). His M.O. is to kill a series of four people in a very specific fashion. The first victim is a young boy, usually around the age of 10, whom he forces to wear pajamas then buries him alive in wet concrete. The second victim is a young woman whom he holds down in a bathtub, cuts the femoral artery and uses a mirror to watch die from bleeding out. The third victim is a mother of 2 kids whom he uses threats to her family to convince to jump off a building to her death. The fourth victim is an older man, also a parent of two children, whom he bludgeons with a hammer. He's immaculate, always careful never to leave any trace of his presence at the scenes of his crimes aside from the trademark ash smudge he leaves his victims pointing to. Through his killings, he's recreating the traumatic deaths of his own family members (If I Had a Hammer). He performs this cycle roughly once or twice every year, during school breaks. His first cycle took place in Miami. 30 years later (Living The Dream), he returned to exactly the same locations and killed there again.
In Road Kill, Arthur revealed his back story to Dexter. When he was 10, in 1959, he walked in on his sister, Vera, showering. When she saw him and panicked, she slipped and smashed the shower doors' glass, her femoral artery being slashed in the process. His mother, Marsha, then became very depressed and killed herself the following year by jumping off a roof. His father, Henry, started drinking heavily, became more abusive and beat Arthur as a result of these deaths, blaming him for them. He too was killed in 1964 when he was bludgeoned to death with a hammer in an alley (Dexter theorizes that Arthur himself was the killer. He would have been 15 at the time). The first victims of the cycles, the young boy dressed in a pajamas and placed in wet concrete, is supposed to symbolize Arthur himself on the night of Vera's death, his last moment of innocence.
Despite Arthur's serial killing, he still manages to maintain a family life with his wife, Sally, and two children, Jonah and Becca, who he genuinely loves. He works as a high school teacher and is also a deacon and the leader of Four Walls, One Heart, a charitable Christian home building organization, which he uses as a cover for his travels throughout the country. He keeps his home building plaques as trophies for his killings. It was, however, revealed in Hungry Man that Arthur is extremely controlling, domineering and even verbally and physically abusive, his family keeping up the facade of a happy suburban family. He also has an adult daughter, Christine Hill, from a past relationship. In Dex Takes a Holiday, she shot Debra and Lundy, killing him, in order to protect Arthur; when she was five, she had witnessed him performing one of his bathtub murders. It was initially believed by some that Arthur had been the shooter and by some that Nikki Reed, one of the Vacation Murderers, did it. Eventually, Christine was caught and killed herself after confessing.
Because Arthur had apparently escaped (and was never known to have been killed), the FBI continued to chase after a ghost while his family is put into the witness protection program. To this day the only ones that know Arthur is actually dead are Jonah Mitchell and Dexter himself (Dexter also tells Isaak Sirko and Debra Morgan that he killed his wife's murderer, although both Isaak and Debra later die).
In Arthur killing Rita Morgan, he creates a downward spiral for Dexter that follows him for quite some time. To try and escape the depression he's hit with, Dexter first kills a man named Rankin who insulted his late wife and then tries to feel alive again hunting a man named Boyd Fowler, which after killing him leads into a confrontation with a woman named Lumen Pierce. Feeling responsible for Rita's death, Dexter attempts to redeem himself by aiding Lumen in avenging her for the rape and torture brought on by Jordan Chase and The Group, killing every member before she's finally freed from her vengeance. Along the way Dexter becomes romantically involved with Lumen but upon killing the last member, her desire to kill vanishes and she sees a future with him as impossible thus leaving him.
Arthur is mentioned at various points as the story progresses, first multiple times throughout helping Lumen and even by her Main Antagonist Jordan Chase, who says he followed the Trinity Case very closely (even saying he admired Trinity, though for his "masked life"). During the Doomsday Killer Investigation, Lieutenant Debra Morgan receives information that both Arthur's wife and daughter were found dead in ways similar to what Arthur used to kill his victims. The FBI, convinced by surviving family member Jonah Mitchell, investigates the possibility that Trinity has returned. Dexter leaves for Nebraska to find out what happened and learns that the daughter killed herself due to the high pressures that their mother put her under and Jonah killed his mother out of anger and vengeance. Dexter ends up forgiving him for this and leaves, choosing not to kill the only remaining member of the Mitchell family despite initially feeling he may have went down his father's path.
Cycle of Kills
Due to his life as a school teacher, Arthur Mitchell's cycles took place within the school holidays. He also usually committed his murders while out of town with Four Walls One Heart. The plaques he received for his part in building new homes served as his trophies. In Season Four, Arthur carried out a cycle during the December break. The pattern was as follows:
- The 10 year old boy represents Arthur before he saw his sister die. Having the boy play with his toys and placing him in wet concrete in the foundation of the house he helps build, preserving the body inside, is Arthur's way of symbolically preserving his own innocence from his life before the incident.
- The woman bleeding out in the tub represents Arthur's sister, who was accidentally killed when she was startled by Arthur in the shower. She fell, broke the shower door, and bled out right in front of Arthur.
- The woman jumping from the building represents the suicide of his mother. Arthur is extremely particular about making them jump themselves rather than him pushing them.
- The final kill represents the death of his father, who was killed in an alleyway with a hammer. They are arguably Arthur's most violent and sadistic kill in the cycle because of his deep hatred for his own father, who abused him.
- 2006 September 10 - Mark Wolter (age 10)
- 2007 August 11 - Thayer Copperud (age 10)
- 2008 September 15 - Brody Avenir (age 10)
- 2009 July 9 - Mathew Hicks (age 10)
- 2009 September 16 - Christopher Kavanaugh (age 10)
- 1979 - Vicky Noonan (age 22)
- (Missing years)
- 1993 March 12 - J. Lewitt
- 1994 September 5 - I. Rosengard
- 1995 February 26 - A. Darakjan
- 1997 February 12 - Loretta Kellerman
- 1997 September 16 - M. Bogert
- 1998 August 23 - L. Candace
- 1999 March 9 - J. Spaan
- 1999 October 7 - H. Grodman
- 2000 March 3 - Anita Soloman
- 2001 March 11 - L. Fisher
- 2002 October 24 - R. Goldman
- 2003 April 15 - K. Watkins
- 2005 May 11 - A. Goff
- 2006 September 18 - J. Meltzer
- 2007 July 20 - R. Cornelius
- 2007 August 16 - Tamera Klaman
- 2008 July 20 - L. Spheeris
- 2008 September 9 - Julie Hillard
- 2009 September 21 - Lisa Bell
- 1993 March 17 - D. Webster
- 1994 September 10 - E. Hemming
- 1995 March 3 - N. Reiss
- 1997 September 21 - J. Snisse
- 1998 August 28 - R. Elliot
- 1999 March 14 - R. Golden
- 1999 October 14 - C. Endless
- 2001 May 16 - P. Ford
- 2002 October 29 - J. Lewis
- 2003 April 20 - A. Asarcca
- 2005 May 16 - L. Pickford
- 2006 September 23 - J. Antonoff
- 2007 July 25 - R. Hermosillo
- 2008 July 25 - J. Leiberman
- 2009 September 26 - Tarla Grant (age 36)
- 1993 March 22 - S. Hunter
- 1994 September 15 - J. Roberson
- 1995 March 8 - D. Freiburn
- 1997 September 26 - E. Newman
- 1998 September 2 - R. Dermott
- 1999 March 19 - B. Ball
- 1999 October 19 - F. Calvert
- 2001 May 21 - A. Severse
- 2002 November 3 - C. Moreno
- 2003 April 25 - J. Jones
- 2005 May 21 - A. Roman
- 2006 September 28 - J. Ellis
- 2007 July 30 - B. Polaski
- 2008 July 30 - R. Bear
- 2009 October 1 - Earl Doorman
The following victims are the few kills that Arthur has made outside of his kill cycle.
- Henry Mitchell - Arthur's father. Although it is never confirmed, due to the things Arthur shouts at his bludgeoned victims, it is probable that Henry was Arthur's first kill.
- Kyle Butler - Another victim that he bludgeoned while he was trying to find Dexter. This one was done after he had failed at starting a new cycle. This man doesn't fit into Trinity's cycle because Arthur just wanted to kill him to silence him.
- Rita Morgan - A bathtub victim. She is considered outside of his cycle for two reasons: He had yet to succeed in burying a young boy in cement, and she didn't fit the normal characteristics of his bathtub victims. Of special note, Arthur is the second Main Antagonist to kill a main character in the series (with his final victim being Rita Morgan). Before that, only Lila West had killed a main character - the imprisoned Sergeant James Doakes.
- Vera Mitchell - accidental death; she was surprised by Arthur while she was in the shower. She fell, broke the shower door, cut her femoral artery, and bled out.
- Frank Lundy - was shot by Christine Hill, who tried to save her father from being caught.
- Stan Beaudry - was killed by Dexter because he needed someone to frame for Trinity murders.
- Rebecca Mitchell - Rebecca, committed suicide in a fashion similar to the bathtub victims.
- Sally Mitchell - was killed by Jonah Mitchell because of her abusive behavior due to growing obsession with Arthur, which was the reason for Rebecca's suicide.
- Jonah Mitchell
- Scott Smith
- Kyle Butler
- Debra Morgan - indirect attempt; shot by Christine Hill, but survived
- Frank Lundy - Was believed for some time to be a victim of Trinity, until it was confirmed that person who shot Lundy and Debra Morgan was shorter than Trinity.
- Rebecca Mitchell - She actually commited suicide in a bathtub, though Debra thought that Trinity was the one to blame.
- Sally Mitchell - She was killed Jonah Mitchell, but Debra also believed her to be a victim of Trinity.
- It is never shown, but it's quite possible that planted evidence in the apartment of Stan Beaudry was eventually traced back and Arthur was connected to disappearance.
|First theme music for Trinity|
|Trouble with the audio sample?|
Arthur has two unique theme songs that are both available on the Dexter Season 4 Soundtrack named Introducing Trinity and the Trinity Suite. Each of these themes illustrates all the proper personality effects of Trinity: he's a survivor that has lasted for over 30 years as a Serial killer and it depicts the fact that he is a man with a dark nature.
His theme music is later used in Season 6, Episode 7, when Debra tells Dexter about the murder of Trinity's wife and daughter and when Jonah walks towards Dexter, as well as in Season 7 for Ray Speltzer.
- Arthur was originally named Walter Simmons.
- Arthur's wife's name is Sally, which was the name of the sister of John Lithgow's character in 3rd Rock from the Sun.
- It's interesting to note that Arthur has killed Rita, as both John Lithgow (Arthur) and Julie Benz (Rita) have each appeared in Sylvester Stallone's movies. Lithgow played the main antagonist in Cliffhanger, while Benz appeared in Rambo, playing a damsel in distress.
- Arthur is the only main antagonist to have had the full routine Dexter goes through when he claims a victim applied. He's the only one to have been killed by Dexter, dismembered, dumped into the gulf stream, and have a blood slide taken and placed into the blood slide box. Likewise, he was the first for all of this as well.
- Brian Moser didn't have a blood slide taken, and his body was left for the police to find.
- It is unknown what Dexter did to Lila West's body after killing her, but he didn't take a blood slide from her, since he wasn't seen placing one into the new box.
- Miguel Prado was killed in an M.O. similar to George King's, so he didn't have a blood slide taken.
- Jordan Chase was dismembered and dumped into the gulf, but he didn't have blood taken, and most importantly, was not killed by Dexter, but by Lumen Pierce. He was also the last main antagonist to be dismembered.
- Travis Marshall was killed and had a slide taken, but since Debra walked in on Dexter, he was not dismembered or disposed of properly. Instead, with Debra's help, Dexter burned Travis' body and made it look like a ritualistic suicide, leaving it for the police to find. Dexter also lost the blood slide at the crime scene, which was later found, broken and partially burned, by Maria LaGuerta. Also, Travis was the last person Dexter took a blood slide from, as he later abandoned this practice when Debra discovered he was a serial killer after finding his slides.
- Isaak Sirko, although not killed by Dexter, was presumably dropped into the gulf river, where Dexter took him so that he could be with Viktor Baskov, Isaak's lover and a previous victim of Dexter's.
- Oliver Saxon was killed in a police station, in self defense, so his body was presumably autopsied and later buried or cremated.
- Interestingly, Arthur is the first main Antagonist to be dumped in the golf stream. After we see Dexter bludgeoning him to death (off screen, but we see him drop the hammer to his face in one shot) and then we see Dexter throwing bags containing Arthur's corpse.
- He is the oldest main antagonist in the series, as Professor Gellar was technically not the main antagonist of Season Six, despite being 65 at the time of his original death (which was prior to the events of that season). Walter Kenney is the oldest known victim overall, being killed at age 73.
- He is the first antagonist to affect Dexter's life partially (since he killed Rita in season 4, and Dexter grieved for her throughout season 5). The second to do so was Oliver Saxon, the antagonist of Season 8. He killed Dexter's protege, Zach Hamilton, killed the woman who originally made the code, Evelyn Vogel, and shot Debra, which eventually lead to her going brain dead and giving Dexter a reason to mercifully kill her.
- Travis Marshall was close to doing the same, as he threatened to kill Dexter's son, Harrison, but failed to do so. Isaak Sirko held Hannah McKay hostage but fully intended to let her go free if Dexter helped him and Maria LaGuerta nearly had him arrested for being the Bay Harbor Butcher but failed and could have also brought down Debra Morgan later on.
- Arthur is the second person who found out Dexter was using an alias around him, and discovered his real name, the first one was Zoey Kruger.
- He is the second main antagonist to be married (the first being Miguel Prado), and the first (and only) to have children. That said, it is unknown, however unlikely, whether or not Stan Liddy was ever married or had children, as he is in his late 50's and very little is known about his past.
- Arthur is the first main antagonist of the series who was not only present in all episodes of the season, but was also a threat all throughout; Season 1's Brian Moser, while being the central threat throughout the season, did not appear in all of its episodes; Season 2's Lila West was absent for the season's first two episodes; and Season 3's Miguel Prado, while appearing in all episodes of the season, only appeared as a corpse in the season finale, and thus did not serve as a threat then.
- In addition, Season Five's Jordan Chase did not appear until halfway through the season, Season Six's Travis Marshall was shown to be a protagonist for a majority of the season only to be revealed as the main antagonist (to even himself) near the end and Season Seven's Isaak Sirko died nine episodes into the season, dying as a protagonist rather than antagonist. Maria LaGuerta was a main protagonist for the first six seasons and slowly became a main antagonist for the seventh season, finally sprouting after Isaak's death (though not linked).
- He introduced himself to Tarla Grant as Alan. It can be reference of Alan Grant, the main protagonist of Jurassic Park movie.
- Both of his daughters committed suicide.
- It is remotely possible that parts of Trinity's character were based on Dennis Rader, the BTK (Bind, Torture, Kill) killer. Both held prominent positions in their churches; both had a family; and finally, both of them had a specific routine they followed. Trinity's process could be considered a much more drawn-out version of BTK's murders, with the cement burials being the binding, the bathtub kill being the torture, and the last two being the typical "kill".
- Walter Kenney, The Tooth Fairy Killer, a similar older serial killer