|“||That's why I need to do this. I need you to hurt...the way I hurt.||”|
— Mark to his husband
Mark's parents divorced when he was six years old. Whenever he was in his father's custody, Mark was forced to work in his butcher shop while his father sat elsewhere idly and drank. This caused him to develop a fascination with dismemberment and cutting meat. Later, his mother successfully petitioned for full custody over Mark, with his father never fighting against it. Afterwards, he never saw his father again. This paternal neglect warped Mark's mind and caused him to develop severe abandonment issues. As an adult, he realized that he was gay, and he eventually married another gay man named Bill Seavers. However, Mark was extremely manipulative, possessive, and domineering over Bill, eventually causing Bill to file for divorce and leave the house. Enraged by this loss of control, Mark attacked a man named Paul Mastriano, who resembled Bill, stabbed him to death, and dismembered his body. The torso was conveniently discovered by a stranded female motorist, prompting the BAU to be called in.
A Good Husband
On the next night, Mark sets his sights on another man named Brent Miller. As a drugged Brent phones in a message to his wife Lisa on the phone, while stumbling around in an alleyway, Mark ambushes, incapacitates, and dismembers Brent with a meat cleaver. He then dumps Brent's remains in a parking lot, which are found by pedestrians. The following day, Mark is seen in his apartment drinking while Bill returns to pack up all of his belongings. As he does so, Mark first tries to remind Bill that he made a commitment to him and that they have waited three years to get married. Then, Mark asks Bill if he is romantically involved with another man and wants him to tell him, as he owes him that. Bill doesn't respond to that question, instead he tells Mark that he is being paranoid. Then, Bill's friends Kate and Diane call, which disturbs Mark, but Bill tells him that they are the only friends he has left, adding that they care about him and they don't make him feel useless. As Mark promises Bill that he will try to seek help for his tendencies, Bill starts to watch a news report about Mark's second murder.
Moments later, Kate and Diane arrive. Then, Mark tells Bill that he loves him and would do anything for him. He then accuses Kate and Diane of manipulating Bill, and shows him their wedding photo, telling him that this is who they are. However, the three of them are disgusted by him and leave the apartment. Despondent, Mark goes to drink at a bar the following night and is approached there by Dale Ericsson, a friend of his and Bill's. As they both talk and have a beer, Dale tells Mark that they should leave the bar since it is too loud, and Mark acquiesces. Outside, he takes Dale to his van and dismembers him alive. Then, Mark dumps Dale's remains in an alleyway in the gay community. The following day, a panicked Bill comes to Mark's apartment to tell him about Dale's murder and that he wants to know if he is safe. Bill then notices a cut on Mark's hand, but he claims that he caught it on the latch when he was loading his van. Later, Bill learns from the news that the new victim was Dale, and Mark convinces him to stay with him tonight, saying that they need each other; Bill initially refuses, but eventually gives in at Mark's prodding.
Later, Bill tries to go to the bathroom while Mark is making him some chamomile. Seeing this and realizing that Dale's bloodied clothes and his meat cleaver are still in the bathtub, Mark manages to stop him. He assuages Bill by apologizing for pushing him away, then he kisses him and convinces him to use the master bathroom. That night, while Bill is sleeping, Mark returns to the bathroom and cleans the cleaver, the clothes, and the bathtub. Afterwards, Mark finds that Bill is gone. He tracks him down to a bar called Rebecca's and sees him talking to another of their friends, Wesley Parham. When Mark sees Bill and Wesley hug each other, he believes Bill is cheating on him and eventually approaches Wesley when Bill leaves the bar. He pretends to ask Wesley if he has seen Bill, but Wesley replies that he doesn't want to talk to him. Then, Mark pretends to acknowledge being a terrible friend by cutting Bill off from him, and tries to make it up to Wesley by offering him a drink. However, he slips a drug into Wesley's drink and, once he is incapacitated, Mark takes him to his van, where he kills him.
The following morning, after Wesley's remains are found and identified, Mark, Bill, and a number of other gays go to a makeshift memorial and put flowers there. Unbeknownst to them, the BAU is surveying the entire crowd in their SUVs, taking pictures of every member as part of their search for the unsub. Mark and Bill then go to a restaurant to have a drink and discuss about conditions for Bill to drop the divorce filing. Bill explains that if he wants to come back, it has to be done on his own terms, and he makes Mark promise not to push away his friends. They later return to Mark's apartment, where Bill adds that he wants to invite friends over and be more independent; Mark agrees to it. However, during the conversation, Mark accidentally lets it slip that he knew Bill and Wesley met up at Rebecca's, which enrages Bill when he realizes that Mark followed him there that night. He tries to leave the apartment, but Mark grabs his arm and angrily accuses him of cheating on him with Wesley. As Bill steadfastly denies it, he deduces that Mark is the one who killed Wesley and the other men.
They both get into a struggle as a result. Mark gains the upper hand, strangling Bill and snarling that this is all his fault and that he broke the rules. Bill breaks free and assaults Mark, temporarily incapacitating him. He tries to call 911, but Mark gets up and bludgeons Bill into unconsciousness with a horse figurine. A few minutes later, Bill regains consciousness and finds Mark restraining his wrists and ankles with duct tape. Bill tries to reason with Mark by telling him that he loves him, but he puts duct tape over his mouth while saying that this is why he needs to do this and that he wants him to "hurt the way [he] hurt". Mark grabs the meat cleaver and is about to kill Bill, but the BAU show up, having identified Mark as the unsub. Reid, JJ, and Prentiss hold him at gunpoint and order him to drop the meat cleaver, which he does. As Mark is being handcuffed and dragged away, he tells Bill that they are still married, then invokes spousal privilege. Mark is last seen being taken away by JJ and a police officer, and he and Bill lock eyes at each other. Soon after, Reid informs Bill that spousal privilege only applies to conversations between spouses, and that Bill can still testify in open court about what Mark tried to do to him.
Mark initially targeted blond, lean, healthy men who resembled Bill and were at bars drinking alcohol at the time. However, as he became more focused in his killings, he started targeting people connected to him and Bill. The victims were all mentally incapacitated by date-rape drugs placed in their drinks, then dismembered with a meat cleaver in Mark's van and the pieces disposed of, with the torsos always being the easiest to find.
For his first two murders, which were committed out of rage, Mark stabbed the victims repeatedly with a meat cleaver and dismembered them with the same weapon. The first victim, Paul Mastriano, was stabbed to death and decapitated and dismembered post-mortem, with the torso being hidden away in a dumpster. The second victim, Brent Miller, was also stabbed repeatedly, but the dismemberment occurred ante-mortem; the torso was not hidden away and instead left in plain view. In both cases, the victims were straight and had relationship problems, just like Mark. Starting with his third murder, however, Mark became more focused in his victimology. The third victim was gay, and was fatally dismembered without being stabbed; the torso was then left in a public place frequented by the gay community as shock value.
During his fourth murder, Mark targeted a gay man who was a friend of Bill's and an acquaintance of his. Much like the previous victim, he was fatally dismembered without being stabbed, and the torso dumped in a public place frequented by the gay community in order to frighten Bill into staying with Mark. When Mark tried to kill Bill, he first manually strangled him, but when Bill assaulted him and escaped, Mark bludgeoned him into unconsciousness with a horse figurine. Then, he restrained his limbs with duct tape and attempted to dismember him with the cleaver.
The unsub is a local white male in his 30s with control issues. He may be homosexual or bisexual, and he has been harboring a kill fantasy. Until now, he has been able to sublimate his homicidal urges by controlling his work environment or his relationships. He may not be physically imposing himself, which is why he drugs his victims to paralyze and control them. He then dismembers them as a form of torture before decapitating them because this gives him the ultimate feeling of power. It is also a way to depersonalize them, or intentionally negate the characteristics that make them uniquely human. He may be disposing his victims' limbs and heads by putting them in dumpsters or in shallow graves in the desert as a forensic countermeasure. The torsos he leaves for display are his trophies and he wants them to be found. Each victim so far has been blond, healthy, and slim, meaning he has a preference. They are most likely surrogates for a current or former romantic partner, or even a spouse who he controlled through nonviolent manipulation. It is believed he may have been rejected recently, causing him to escalate to murder in order to regain a sense of control.
Mark seems to have been based from a variety of real-life homosexual serial killers. They include:
- Robert Berdella, a.k.a. "The Kansas City Butcher". Both were homosexual killers who had troubled childhoods involving their fathers, and targeted fellow gay men (including acquaintances of theirs), who they would mentally incapacitate with drugs and alcohol. After killing their victims, both Mark and Berdella dismembered the bodies and disposed of the body parts, with the dismemberment being learned beforehand in their occupations (Mark worked in his father's butcher shop as a child, while Berdella once worked as a successful full-time chef).
- Larry Eyler, a.k.a. "The Highway Killer". Both were homosexual serial killers whose parents divorced when they were children, had troubled childhoods involving their paternal figures, targeted homosexual men, incapacitated their victims with drugs, and had M.O.s that involved stabbing and dismemberment.
- Jeffrey Dahmer and John Wayne Gacy, according to Lewis. All three were psychopathic, homosexual killers with troubled childhoods, who incapacitated their victims with drugs and alcohol. Like Dahmer, Mark's parents divorced when they were young, and he shared Dahmer's abandonment and control issues, as well as Dahmer's victimology (homosexual Caucasian males) and tendency to dismember his victims (Dahmer did it post-mortem, while Mark did it ante-mortem). Like Gacy, Mark was raised by an alcoholic father and had a spouse who left him prior to the killings; he also killed his first victim by stabbing him to death.
- William Bonin, Patrick Kearney, and Randy Kraft, the so-called "Freeway Killers". All four were homosexuals who targeted males and operated in California. Like Bonin, Mark tortured and killed his victims inside his vehicle, and performed overkill on the bodies. Like Kearney, Mark was in a longstanding relationship with another man (though Mark's husband legally left him prior to his killings; whereas Kearney's lover, David Hill, was still with him when he committed his murders), found his victims in bars, killed his victims in his vehicle, and dismembered their bodies (though Kearney did it post-mortem, while Mark did it as a torture method with his last three victims). Like Kraft, Mark found his victims in bars, incapacitated them by lacing their drinks with drugs, and tortured them before killing them.
- Dennis Nilsen, a.k.a. "The Muswell Hill Murderer". Both were homosexual killers whose parents divorced while they were minors, were in relationships with men that ended prior to their killings, targeted fellow homosexual men, found their victims in bars, and dismembered their victims (Mark did it as a form of torture with his last three victims; Nilsen did it post-mortem).
- Stephen Port, a.k.a. "The Grindr Killer". Both were homosexual killers who targeted fellow homosexuals and incapacitated them by lacing their drinks with drugs before assaulting them. However, in Port's case, the victims were killed by the drugs, whereas Mark's victims were not.
In addition to all of these killers, Mark has some similarities with an uncaught serial killer, the Mad Butcher of Kingsbury Run. Both Mark and the Butcher dismembered their victims completely (although the Butcher dismembered all of his victims post-mortem while Mark did it ante-mortem with his later victims), with the torsos always being found first. The Butcher's first identified victim, Edward W. Andrassy, was an alleged bisexual and had several homosexual friends, while police searched for suspects in gay bars; these could have been used as references for Mark's sexual orientation and selection of later victims. Mark also has some similarities to suspected serial killer Paul Bateson, who was alleged to have met his victims in bars, charmed them to secluded locations, stabbed them to death, and dismembered their bodies.
Also, Mark has some similarities with British serial killers Colin Ireland, a.k.a. "The Gay Slayer"; and Peter Moore, a.k.a. "The Man in Black". All three targeted homosexual men and met their gay victims in bars. Like Ireland, Mark tortured his victims before killing them. Like Moore, Mark killed his victims by stabbing them to death. Unlike Mark, however, both Ireland and Moore were not homosexual themselves, and had different motives for targeting gay men.
Finally, the early episode discussion about the dismemberment being a possible strategy to ensure difficult identification and the killer most likely being a local, if he was capable of getting rid of a torso in a large city without suspicion, is similar to law enforcement's ideas about the earliest crimes of the Gilgo Beach Killer.
- February 5: Paul Mastriano (stabbed repeatedly and dismembered post-mortem)
- February 6: Brent Miller (stabbed repeatedly and fatally dismembered)
- February 7: Dale Ericsson (fatally dismembered)
- February 8:
- Wesley Parham (fatally dismembered like the previous victim)
- Bill Seavers (his husband; non-fatally manually strangled and bludgeoned with a horse figurine, then tied up and attempted to dismember alive)
- Mark is based on a few other unsubs:
- Michael Janeczco, a serial-turned-spree killer who appeared in Season Seven. Both were motivated by their spouses leaving them, initially targeted men who had relationship troubles, found their victims at bars, and incapacitated them in some manner that involved alcohol. In both cases, their last murder victims were men who were associated with them and at least one of their relatives (Mark's last victim was an acquaintance of his, and a friend of his husband; Michael's last victim was his former best friend, and his stepson's biological father). Both also killed one victim by stabbing and dismembering them. In addition, Mark being homosexual is an allusion to the BAU suspecting that Michael was of the same sexual orientation.
- Paul Westin, a serial-turned-spree killer who appeared in Season Eight. Both were homosexual spree killers who killed their victims by stabbing them, but unlike Paul, Mark was not abused by any father figure for being homosexual.
- Steven Parkett, a serial killer who appeared in the Season Ten premiere episode X. Like Mark, Parkett was motivated by relationship troubles (though his circumstances were different from Mark's), had an abusive father, was based on Robert Berdella and the Mad Butcher of Kingsbury Run, and dismembered his victims alive as a form of torture.