Phillip Bosso is a Character in DEXTER. He is an Arson Investigator in Miami and first arrives at one of the crime scenes caused by the Phantom Killer. He's shown to be somewhat of a quirky individual, causing jumpscares even to Dexter Morgan at his sudden appearances.
Phil is a Caucasian male in his late 30's to early 40's. He has a receding hairline, with combed back hair and bright blue eyes. His shown attire is that of a fire inspector, with a white uniformed shirt provided with his badge and identifying patches included with black dress pants and shoes. On one occasion he wears a cowboy hat and decorated coat, often worn by rich tycoons out west.
Phil initially appears to be very versed in arson and the way fire can kill a human being, often correcting (and on occasion, rudely interrupting) others in describing a crime scene. He's prone to showing up unexpectedly, resulting in "jumpscares" to anyone caught by surprise. Despite this, he is an intelligent man who is good at his job and has been seen at several of the Phantom Killer's crime scenes.
Unknown to others, Dexter Morgan begins to witness a change in Phil's personality around the corpses of the Phantom Killer. Phil almost seems reminiscent of their bodies, looking thoughtfully at them letting his expression die out as he almost seems lost in their presence. Dexter doesn't put much focus on him initially, due to having problems with Isaak Sirko at the time but with more bodies piling up, his "instinct" tells him something's off about Phil, possibly viewing him as the actual Phantom Killer. Dexter then looked into his background and discovered Phil is very good at his job, having a 92% solve rate in arson investigations, prompting Dexter to believe he is the killer. He tracks him down to a park and sees sparklers and fires and sees Phil in a Southern war outfit revealing Phil to have a strong love for American History as he was just part of a Civil War reanactment scene. This, coupled with him being friendly to Dexter showing pictures gave Dexter relief he isn't the Phantom Killer but someone who's good at his job and a little eerie.
After a grueling month dealing with the Doomsday Killer Investigation, Travis Marshall is finally killed by Dexter Morgan and to help cover up the murder that she walked in on, Debra Morgan agrees to aide in disposing of the evidence. Dexter fills the Santa Maria de Laredo with gasoline and lights it ablaze, burning Travis along with any identifying evidence (while also placing the John the Revelator Sword into his chest to make it appear as a suicide). Phil apparently met with Lieutenant Debra Morgan the day after, however he can not be seen at this crime scene (though he claims otherwise however one firefighter in full retardant gear shares a slightly similar appearance to him). Vince Masuka does mention that the Arson Investigator stated that the fire started somewhere in the middle of the church with the melted remains of the gas cans confirming that.
Some time passes to near the end of Dexter Morgan and Isaak Sirko's feud. A body is called in, which Dexter gets the notice on and he arrives on the scene. Sergeant Angel Batista, Vince Masuka and Angie Miller are standing near a charred car, burned from the inside with a scorched corpse sitting upright in the driver's seat. Dexter asks if he can get a closer look but upon doing so, Phil Bosso pops up outside the passenger side hitting the door in the process. He says he'd rather Dexter not do that, at least until he's had a look at the scene himself...the sudden appearance startling Dexter while Batista snickers on.
Phil heads into the back passenger side door, examining the back seat as he notes an empty bottle of accelerant and an oily residue around the interior. He also locates an ID card, which he hands to Batista. Lieutenant Debra Morgan arrives and asks what's going on, only to see Phil pop up out of the car startling her just like he did Dexter. He reintroduces himself, saying they met back at the "church burning" (Travis Marshall's church). The victim is revealed to be Danny Yamiro, a Paralegal that works downtown from there.
He goes on to say that he thinks they have a suicide here, with Masuka stating "harakiri" (a form of suicide). He says it's self-immolation but Phil corrects him saying it's actually self-incineration, with immolation covering more than just fire. Dexter examines the backseat and questions him about the burn rate, asking if he's sure it's a suicide (suggesting possible murder). Phil mocks Dexter a bit by asking if he's the blood guy and after Dexter confirms this, he simply says "exactly" (hinting that because he's the arson investigator, he would know more about a fire crime scene than someone who specializes in blood).
Dexter receives a call to come to another crime scene, this time in the parking lot for MSU (a Miami University). A body is found inside an elevator here, where Phil is already looking over it as Dexter walks in. The victim is ID'd as Leo Santolongo, a college grad student who was a "punch away from free coffee". Phil goes on to detail that the same accelerant was used at this crime scene, a petroleum-based construct along with what appeared to be fuel poured over his head. Dexter notices something on the wall, and tells the others to close the elevator doors, leaving him and Phil alone in the elevator. With the doors closed, Dexter now realizes the word reads Bobby, possibly indicating the name of the killer. As he investigates, Phil becomes somewhat uneasy.
Phil arrives on scene following an arson with the death of a mother and her 6-year old child stating the same accelerant was used just like the other ones. He looks at the little girl prompting Dexter to wonder if he's the killer himself. He arrives at Miami Metro to talk about the killer who's likely egocentric and insane. Dexter later looks into Phil's background and discovers he has a 92% investigation record and notes he's either good at his job or knows how they started because he started them. He tails him to a park and finds sparklers and things to set a fire, causing Dexter to believe he's the Phantom Killer. However, Phil appears and asks what he's doing and just says he's also a war fan prompting Phil to react surprised and the two talk about American History with Phil showing some pictures on his phone and Dexter reallizing to himself that Phil isn't the Phantom Killer, but someone who's good at his job and just slightly creepy.