His modus operandi (M.O.) serves not only to maximize the satisfaction he derives from his kills, but to eliminate forensic clues and evidence, and to ensure that he does not target innocents.
The kill itself is a well planned and thought out process that follows these basic steps:
Dexter almost always targets murderers who acted without regret and evaded conventional justice. At times, Dexter's picks are also being hunted by The Miami Metro Police Department, e.g. Arthur Mitchell. There is one instance in which Dexter, aided by Miguel Prado, busts a convict out of prison in order to kill him (the twist was that the convict committed murder by proxy from prison).
To find targets, Dexter pays attention to unsolved cases, blood reports from fellow spatter analysts, and even rumors. Before Camilla Figg died, he used his friendship with her to acquire files on killers released by technicality or judicial mistakes. Also, he finds interesting possibilities by attending court hearings or appearing in court as a forensic witness. Because Dexter spends much of his time working with Homicide, he has extensive access to police databases that provide him with information, names, pictures, and addresses. He often uses the forensic equipment within his own lab to confirm a target's guilt. The means by which Dexter discovers some of his targets is unknown.
According to The Code of Harry, Dexter must confirm the guilt of his target. He spends at least a day acquiring solid evidence against the intended victim. The target is stalked for some time to learn their habits, routines, personal details, and the best time for capture. This includes Dexter using a lock pick to invade the target's living place in order to search the premises. While hunting, he frequently meets his target head on to learn from their conversation. Dexter is a master at faking identities, having nearly a dozen aliases during the course of the show.
Usually, but not always, Dexter kills in a pre-selected place. He prepares a Kill Room by completely swathing it in clear plastic wrap so that blood, sweat, fingerprints, fibers, etc, won't leave forensic evidence. He decorates the room with evidence or pictures of his target's victims, and candles. In one extreme instance, Dexter furnished a kill room with the actual exhumed corpses of the killer's victims.
The center of the kill room contains some form of table for the victim to lay on. Dexter will have rolls of shrink wrap to hold the victim to the table to prevent escape.
His Kill Tools consist of a set of knives, a surgical power saw, and a kit of surgical instruments in a "Messermeister" bag which mixes tools from different areas of craftsmanship - rachiotomy saw, meat cleaver, custom knife, etc. At times, Dexter uses a chainsaw or other items to kill a victim.
Capture usually entails approaching unsuspecting targets from behind and injecting them with M99, rendering them temporarily unconscious. Sometimes, he will use wire or a chokehold to strangle a victim until they are unconscious. Most times, this is done outside of the area where the kill room is located.
After obtaining the victim, Dexter uses either his own car or the victim's car to transport them to the kill room.
In New Blood, Dexter's capture method changed. Matt Caldwell was knocked out impulsively and then brought to Dexter's shed to be killed. On the other occasions when he captured victims, Dexter used Ketamine to knock them out, due to no longer having access to M99.
- In the Dexter Novels, Dexter generally incapacitates his target with a rear naked chokehold or a garrote to cut off blood flow to the brain. As in the TV 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 he sits down. Dexter then uses the threat of asphyxiation to force his victim to drive to his prepared kill site.
5. Kill Ritual
Main article: Kill Ritual
Dexter has an unique sense of justice and he believes that by placing his targets at death's door, he might as well force them to see why they've been brought here. In the act known as the Kill Ritual, Dexter's kill room becomes a shrine for the innocent lives whom his target has killed, lined with photos and momentoes, possibly even video footage, and lit candles.
At the center of the room, his target is held to the table by plastic wrap or duct tape, depending on the strength and size of the victim.They are almost always naked under the plastic wrap, having been stripped of their clothes to allow Dexter to easily cut through their flesh after they die.
Dexter usually allows the victim to wake up on their own, which takes anywhere from 3 to 6 hours after capture. Dexter makes sure that the murderer knows that they are being killed for their crimes. Most of his victims respond with denial of their crimes; however, almost all end up admitting to their crimes in the end.
During the Ritual, Dexter uses a scalpel cut his victim's cheek. He takes a bit of their blood and creates a blood slide from the victim's blood as a trophy.
6. Blood Trophy
Main article: Blood Slide Boxes
Just before the murder, Dexter collects a trophy from his victim so that 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 postmortem) underneath the victim's right eye. He then collects a blood sample which he preserves between two laboratory slides.
Dexter neatly organizes the blood slides inside a wooden filing box, which he hides inside his air conditioner. Following the murder of Ray Speltzer, Dexter gave up on collecting trophies, and cremated the second box along with Speltzer's corpse. When he killed Matt Caldwell, his first kill in almost ten years, Dexter initially improvised a blood slide from two broken pieces of glass before deciding not to take a trophy.
- In the Dexter Novels, Dexter keeps his trophies in a rosewood box in his bookcase.
While he has killed victims in many ways, Dexter will almost always end the ritual by stabbing the victim in the heart. In some circumstances, Dexter kills his victims in the way they had killed theirs, i.e. killing Santos Jimenez with a chainsaw. A method that Dexter used in Season One involved driving into a skull with a cranial power saw.
Dexter's favored method to kill is a fatal stab wound to the heart or neck. For certain victims, he cuts through the neck with a hacksaw or reciprocating saw, or beheads with a cleaver. He often likes to ironically/poetically stage the deaths of killers using elements of their own style (e.g. stabbing Little Chino with his own machete, and dismembering Santos Jimenez with a chainsaw in the same manner in which his mother was killed.
- In the Dexter Novels, Dexter prefers a fillet knife, which involves an extended "exploration."
Dexter dismembers the bodies of his victims, and places the sections inside heavy duty black biodegradable garbage bags. He removes all of the plastic sheeting from the kill room, and verifies that he left no evidence behind. He loads the bags into the back of his vehicle and transfers them to his boat, where he adds rocks to weigh down the bags from near the dock. afterward sealing the bags with duct tape. He then takes the wrapped bags out on his boat and disposes of them by dumping them overboard into a oceanic trench.
In Season Two, this site is inadvertently discovered by scuba divers, so he changes tactics, taking the bodies farther offshore, where they will be intercepted by the Gulf Stream and carried to the North Atlantic. He no longer needs to add rocks. A few victims (including A.J. Yates and Clint McKay) are dumped into the Gulf Stream without being dismembered.
His disposal method can change, dependent on the victims or circumstances. At times, Dexter leaves bodies out to be discovered by the police, such as in the cases of Brian Moser and Ken Olson. Occasionally, an entirely different method is used, such as the cremation of Ray Speltzer.
In New Blood, Dexter's disposal method changed. Due to no longer being near the Gulf Stream, Dexter initially disposed of his first victim in ten years, Matt Caldwell by burying him under his fire pit after dismembering him. When a police investigation into Matt's disappearance began, he initially planned to dispose of the remains in the Iron Mine, before a bear scared him off and prevented this. He eventually burned the remains in the Iron Lake Sanitation Incinerator. Jasper Hodge was left for the police as Dexter was unable to dispose of him due to the police appearing before he could kill him. Elric Kane was initially left where he had been killed, but put under a tarp: Dexter later returned and dismembered him before disposing of him in the incinerator. Kurt Caldwell was dismembered and disposed of in the incinerator. Sergeant Logan wasn't disposed of and was left where he had been killed, due to Dexter not having time to dispose of him.
Staged Crime Scenes
At times, Dexter would stage his murders in order to thwart an investigation.
- Brian Moser - Dexter killed him in his own kill room, using his own method of draining blood
- George King - Dexter threw him out of the Tobacco Warehouse, which looked as if he jumped
- Travis Marshall - Dexter staged the scene to appear that he killed himself in one of his tableaus
- Valerie Castillo - Dexter used her blood slide to frame her husband after failing to dispose of the corpse
- Miguel Prado - Dexter skinned part of his body, which was George King's M.O.
Staged Double Murders
- Dan Mendell and Lance Robinson - Dexter set up the area to appear as if a gay couple killed themselves during a fetish session
- Hector Estrada and Maria LaGuerta - Dexter staged the scene to look like Estrada and LaGuerta shot each other
Staged Deaths by Natural Causes
- Camilla Figg - Dexter poisoned her as a form of euthanasia and passed it off as lung cancer
- Walter Kenney - Dexter suffocated him to make it look like he died from a heart attack
- Dexter typically kills his victims by stabbing a knife into their hearts. Other ways include beheading, puncturing/slashing arteries, bludgeoning, impaling, dismembering, strangling, drowning, and neck snapping.
- Injecting a target with a tranquilizer is a tradition that began with his first victim, Nurse Mary. He started to use the alias Patrick Bateman, M.D. (the serial killer in Bret Easton Ellis' film American Psycho) to procure M99.
- When Dexter killed Boyd Fowler, he wore a yellow "Natural Born Griller" apron, yellow dish-gloves, and the shirt he had on prior to his kill.
- When he killed Joe Walker, he wore the Mascot Panther Head from his high school during his stalked kill at his high school reunion.
- When he killed Jamie Jaworski, Dexter wrapped his own head in shrink wrap, leaving only his eyes and mouth visible. The television series left the reason for this unclear; however, the scene is consistent with the same kill in the first Dexter book, Darkly Dreaming Dexter. The book says that, even though the victim was researched and selected as normal for Dexter, the kill itself at the construction site was done on impulse. Dexter experienced such a strong urge to kill that it overpowered his otherwise careful and calculating methods. The plastic wrap was on hand and used in place of his visor. Dexter had to leave Jaworski's body behind when the police suddenly arrived on the scene.
- In "New Blood", when Dexter returns to killing, he still sticks to his old methods. However, he also strays from them in some ways with every one of his kills. His first kill after his ten year hiatus was quite sloppy and rusty, as he didn't properly vet Matt Caldwell, impulsively knocking him out and killing him. Though he had planned to use his normal methods when killing Jasper Hodge, he was forced to kill him by forcing him to overdose when the police showed up, with Jasper also being a kill for more vengeful reasons. Elric Kane was killed without being tied down to any table, being killed once he'd given Dexter the information he needed and to a degree in self defense. Kurt Caldwell was the only kill who almost strictly adhered to Dexter's usual MO, as he had more than enough evidence of Kurt's guilt, he was wrapped in plastic and restrained to a table, as well as being killed by the usual method of being stabbed in the chest.
- Kill Tools
- Kill Room
- Kill Ritual
- Slice of Life
- Dexter's Kill List
- Blood Slide Boxes
- Bay Harbor Butcher Case
- Locations of Dexter's Kills
- Underwater Graveyard
- Gulf Stream
- Serial killers rarely change their basic modus operandi, except for variable details. However, a serial killer may use different methods to keep the police off-track.
- Arthur Mitchell used four different techniques in a kill cycle, which made it difficult to tie all the crimes to one person.
- When Dexter doesn't use his favored methods, it's usually to ensure the first rule of the Code of Harry: "Don't get caught."