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Modus Operandi

Modus operandi (translated from Latin as "method of operation"; often shortened in English as M.O.) is a term used extensively in criminal investigations. It refers to the personal habits of a criminal which form a recognizable pattern each time he commits a crime. The M.O. is the way that the predator commits the crime - for example, if he uses a gun rather than a knife - and his technique for the capture. While a serial killer's M.O. usually only differs slightly from time to time, his earliest victims may be killed in a different manner, as his preferred M.O. forms over time. In cases of serial killers with a large number of victims, there may be more out-of-pattern kills due to circumstances.

Signature is a ritual, something that the killer does intentionally for personal satisfaction and isn’t necessary to perpetuate the crime. Evidence of torture is a signature. Dismemberment is a signature. Posing or displaying the victims in a certain way is a signature. Signature is a way of linking cases. Like a real signature, it’s a personal detail that’s unique to the individual.

While the modus operandi. tells how he did it, the signature gives insight into why he did it.

Dexter's modus operandi and signature serve not only to maximize the satisfaction he derives from his kills but to minimize (if not eliminate) forensic clues and evidence, and to ensure that he does not target innocents.

Main method of Operation

Overview and History

Mary, his first victim - While, in the novels, Dexter's modus operandi was nearly formed by High School (as evidenced by an attempted murder of Steve Gonzalez), in the series it started to form when he did his first kill in 1991. In this particular case, Dexter covered an entire room in multiple layers of plastic and donned a full plastic suit with gloves (Casual clothes were worn underneath.) He then waited for Mary with a syringe (which was ironic because Mary herself killed via syringe). Dexter failed to sedate her in this way, though, and was forced to overpower her in hand-to-hand combat. After he stripped Mary of her clothes, he covered her in shrink wrap and duct tape. When she awoke, Dexter reminded her of her crimes (via her special trophies album, where she kept obituaries of her victims). He listened to her last words, stabbed her multiple times, dismembered her by hacksaw, and then tossed her remains into the marshes of the Everglades.

Evolution of his ritual - During his third kill, Dexter showed photos to his victim for the first time. The idea may have been influenced by Mary's album. As with her, Dexter again used a plastic suit when he killed Juan Rinez. When he killed Alex Timmons, he wore a pathologist's apron, and long surgical gloves. Furthermore, Alex Timmons was the first victim from which Dexter collected a trophy - a blood sample on a glass slide. This technique was inspired by Timmons' hunting trophy collection and an improvised cut to Timmons' face, caused by Dexter playing with his military knife. Dexter would sometimes integrate a victim's killing style with his own.

Slice of Life - An important change that happened before the beginning of the series was the manner in which Dexter disposed of his victims. Usually he dumped their remains in the Everglades, but he thought of a better way and bought a fishing boat, which he re-named from "Slice of Heaven" to "Slice of Life." The boat was previously owned by Gene Marshall's psychiatrist (who could afford a new one because Marshall had paid him to be viewed as an unstable person in court). Dexter then used the boat to dispose of Marshall's own body parts as he wasn't able to cremate them in an improvised fire. With the boat in his possession, Dexter began to discard his victims at sea. He would put the dismembered body parts into trash bags, weight them with rocks from his dock, and dump them in Bay Harbor (later, the Gulf Stream).

Step 1. Selection

Dexter spends a significant amount of time selecting each victim according to his adoptive father's code, The Code of Harry. Dexter targets multiple murderers who have both acted without regret and somehow evaded conventional justice (both being signs that they easily can commit another murder). There have been several occasions during the series where Dexter chooses victims who are also being hunted by The Miami Metro Police Department, such as Arthur Mitchell and Joe Jensen (though the latter was merely an attempted victim). There was even one occasion where Dexter, aided by Miguel Prado, busted a convict out of prison, just so that he could kill him (the twist was that convict was able to commit murders by proxy even from the prison).

Dexter casually uses different variants to search for those, who can increase his kill count. He pays attention to unusually unsolved cases, fellow blood spatter analysts works, even rumors and any auspicious details in people's lives; used his friendship with Camilla Figg to acquire information on people released by technicality and other judicial mistakes; gone to court himself to find interesting possibilities (it helped that he often came here as a witness), etc.

Step 2. Vetting

Once the victim is chosen, Dexter must be absolutely sure that the choice is right according to The Code of Harry. He spends at least a day confirming suspicions and acquiring very solid evidence against the victim. He also stalks victim for some time to have the knowledge of his/her habits, various details and to choose a moment when victim will be more harmless and unsuspecting. Dexter casually uses a lock pick to invade to victim's living place to find the evidence, follows him/her etc.

Step 3. Preparation


Dexter prepares his kill tools.

Dexter ritually prepares a "kill room" by completely swathing it in clear plastic tarp to catch all spilled blood, sweat, prints and other forensic evidence so as to leave no signs of the murder. He also stages some light to see the victim clearly and, as well, to see what he does himself. As part of the ritual, he confronts his victims with their crimes by decorating the room with evidence or pictures of the victims. This has been taken to both extremes in certain situations. In once instance, Dexter decorated the kill room with the actual exhumed corpses of the killer's victims, while in another, he quickly dispatches Lila after mailing her a postcard with a picture of James Doakes (her victim) on it.

Killing tools are also there and usually they consist of surgical power saw, a kit of surgical instruments and a set of knives in a "Messermeister" bag which mixes appropriate tools from different areas of craftsmanship - rachiotomy saw, meat cleaver, custom knife etc.

Step 4. Capture


The actual capture of his victims differs between the books and the television series.

Television Series In the television series it usually entails approaching the victim from behind and injecting them with an anesthetic (specified to be an animal tranquilizer called etorphine hydrochloride, or M99), which renders his victims temporarily unconscious. The injection is a tradition established with his first victim, the hospital nurse. He used the alias Patrick Bateman (the serial killer protagonist of Bret Easton Ellis' American Psycho) to procure these tranquilizers. Never the less, it's not the only method used and from time to time Dexter uses other variants such as strangling victim suddenly till he/her is unconscious.

Books Other times, Dexter incapacitates his target by using either his hands (employing a rear naked choke hold on the TV series) or a garrote to cut off blood flow to the brain. In the books, as in the opening scene in the television series' pilot episode, he hides in the back seat of his victim's vehicle, then wraps a noose of fishing line around his victim's throat when they sit down. He then uses the threat of asphyxiation to force his victim to drive them to his prepared kill site.

Once they arrive, he will either strangle them into unconsciousness or use the noose to drag them to the kill site proper. In such cases he anesthetizes them once he has informed them of his judgment.

Step 5. Ritual Kill


When victims awaken, they are naked and secured to a table with plastic wrap, further securing stronger victims with duct tape. If he has not already done so, he confronts them with narrative evidence of their crimes. In the novels, the method usually involves an extended "exploration" with various sharp knives; in the television series, Dexter's favored method usually involves an immediately fatal wound to the heart, neck, or gut, with a variety of weapons (most often used are power saw, cleaver and a custom knife, in the novels Dexter prefers fillet knife). He occasionally varies his methods to fit particular victims; he kills Brian by cutting his throat with a silverware dinner knife; he stabs gang lord Little Chino in the chest with (his own) machete; and impales Lila with a knife. He also kills his mother's killer, Santos Jimenez, in the same manner in which his mother was killed; by dismembering him with a chainsaw - these and other examples illustrate that he often likes to ironically/poetically stage the deaths of killers using elements of their own style.

Step 6. Trophies


Just before the murder, Dexter collects trophies from his victims so he can relive the experience. Dexter's trophy signature is to slice the victim's cheek with a surgical scalpel (usually when he/she is still alive but sometimes post-mortem) underneath the victim's right eye and to collect a small blood sample, which he preserves between two laboratory slides. In the TV show, Dexter keeps blood slides from all his victims neatly organized in a wooden filing box, which he hides inside his air conditioner; in the novels he keeps them in a rosewood box on his bookcase.

Following the murder of Ray Speltzer, Dexter gave up on collecting trophies, and burned them along with Speltzer's corpse.

Step 7. Disposal

Ultimately, he dismembers the bodies of his victims into several sections (head is usually in place unless the kill method involved decapitating, for example with power saw), wraps them and the plastic sheeting in biodegradable garbage bags, then adds rocks from the dock where he keeps his boat as anchor weight and seals them with duct tape. He then takes the wrapped bags out on his boat and disposes of them by dumping them overboard into the ocean at a defined location; in the TV series, his dumping ground is a small oceanic trench just offshore. In one episode, it is inadvertently discovered by scuba divers, so he changes tactics, taking the bodies further offshore, where they will be intercepted by the Gulf Stream and carried out to sea.

The disposal method has changed a few times, depending on the victims. At times, Dexter leaves them out to be discovered by the police, such as in the case of Brian Moser. Other times, an entirely different method has been used, such as with Ray Speltzer's cremation.

In recent episodes, the few victims that have been dumped into the Gulf Stream have not been dismembered.

Additional Modi Operandi

Serial killers are rarely changing their modus operandi to the ground, safe for some variable details. If they do, then it's usually a sign of a very intelligent killer with dozens of victims who is not willing to be caught or stopped and intends on continuing without not just being caught, but also not being identified either. Same accounts for cases when a serial killer uses a few different modi operandi to keep police off-track. While the most prominent person in the series to use this technique is Trinity Killer (Arthur Mitchell), Dexter is also varies his methods to even further ensure the first rule of The Code of Harry: "not being caught". Therefore, in specific cases Dexter uses patterns which are quite different to his usual ones. This section collects any such method which was used more then once (though, there are a lot of cases when Dexter killed on the spot out of his usual method).


In the novels, to escape from Moloch's Cult, Dexter was forced to shoot a few people in self-defense with an enemy's gun. A similar situation occurred as he escaped Mar Dorado, although this time no one was killed. In the TV Series, Dexter only killed one victim with a gun (Teo Famosa).

Staged Suicides

Basically, victim, a serial killer is killed in a way that looks like a poetic/ironic suicide that includes some elements of his own style.

  • Brian Moser (was killed in his own kill room and with his own killing table)
  • George King (while this time elements of King's own style were more or less unintentional (a piece of skin was cut due to impact of being thrown on the car), it still added to fact and Dexter could have hoped for something like this throwing body on the moving car)
  • Arthur Mitchell - attempted (Dexter tried to made it look like he accidentally loosened his grip while holding Mitchell from falling down (which basically is what he forced some of his victims to do).
  • Travis Marshall (while the kill was mostly done in Dexter's usual M.O., later disposal was made so that it looked like suicide made, again, in Marshall's own style)
  • Oliver Saxon - attempted (really possible considering that original attempt was done in his own kill room)
  • Also, Jeremy Downs really committed suicide with elements of his own style which was indirectly induced by Dexter.
  • Another unintentional and indirect example is James Doakes, though elements of the style were more of Dexter's own (which is logical, considering that Doakes was framed for some of the murders).

Staged Dual Murders

In this case Dexter murders the first victim, then murders the second and makes it to look like they killed each other for some reason. Earliest similar instance known is Miguel Prado and George King but it doesn't count per se, because while Prado was killed to look like King's victim, King later caught Dexter himself and Dexter made it to look like suicide instead.

  • Dan Mendell and Lance Robinson - were made to look like gay couple which killed themselves during fetish sessions.
  • Hector Estrada and Maria LaGuerta - while LaGuerta was killed by Debra it is still count as an indirect victim of Dexter's and overall he staged situation like Estrada and LaGuerta shoot each other.

Neck Snapped

While it's basically an element of M.O. rather then being it itself it is still an interestingly often used element. Dexter is trained in jujitsu, a martial art which has many of it's fighting moves involving the neck of the person on which it used, so when he needs to kill a person on spot as quick as possible and with his bare hands to do it, he often opts to do it such way. It is at least once was incorporated in two other modi operandi listed before.

List of Kill Methods

As a prolific and variable serial killer Dexter used nearly every known method of killing the person at least once in the span of 8 seasons. Especially if we count some of the indirect murders.

Objects Used To Kill

Because he had a very long and prolific career as a serial killer, Dexter killed with many different objects, both often intended and unusual for killing.



Sharpened Tools

Power Tools

Other Items

Related Pages