John was a mortician married to Linda, a woman who suffered from a form of hypoplasia, being born with her right leg missing at the knee and using a prosthetic to walk as a result. Two months prior to "God Complex", John quit his job at the funeral home he worked at and got the idea to try and transplant a foreign leg onto his wife's knee and got funding from an investor for medical equipment which he set up in his garage. He then began to experiment with leg amputation and transplantation, presumably starting with mice and then moving up to human trials involving unwilling test subjects. His first human trial claimed the life of Richard Hubbel.
"Everything's fine. We just need to operate."
John then abducts Tony Anders and takes him to his garage. Before he can start the surgery, Tony regains consciousness and takes a good look at John's face, which is covered with a surgical mask, before John attacks him and puts him back to sleep. He then removes Tony's right leg without killing him and leaves him at a hotel room. The attack on Tony is what led the BAU to being called in. At the same time, John sets his sights on Carl Timmons, abducting him and taking him to his garage, later removing his right leg and replacing it with Tony Anders'. He then leaves Carl a block away from a hospital, where he dies of gangrene. John begins to feel the pressure when his investor starts demanding to examine data acquired from his experiences. Going over the experiments upon his three victims, he feels that he found what he needs to succeed, going on to sedating Maria Rodriguez. He then calls over Donna Sullivan and abducts her also.
The following night, he kills Maria whilst taking her left leg and putting it onto Donna's. Satisfied with his success, John wakes up Linda and urges her to come with him to the garage, where he intends to amputate Donna's right leg and put it onto Linda's. However, when the two reach the garage, John finds Donna missing, as she regained consciousness earlier and freed herself from her bonds. Donna then ambushes Linda and holds her at knifepoint with a scalpel, but John tricks her to putting her back on him while she heads for the door, allowing him to sedate her again. Linda, realizing what John has been doing, yells at him for hurting others, much to his shock. Just then, the BAU arrive, their guns drawn, and John threatens to drug Donna again, which would prove fatal. Reid urges Linda to talk to John and convince him to put the syringe down. This proves successful when Linda threatens him that she will order the agents to shoot, to which John slowly puts the syringe down. He is then arrested while Linda sobs and exclaims his name in shock.
John targeted people of both genders, varying in age and race. He would use a blood donor van to screen his victims and see which ones were suitable for testing. Once he found a suitable candidate, he would track them down using their contact information and abduct them, likely after luring them in using the van. Injecting an unnamed drug into them to prevent them from fleeing, John would take them to a garage in his home, put them on a gurney and handcuff them to it, and sedate them with nitrous oxide.
His signature was the crude amputation of their legs. While Tony Anders' leg was cut above the knee, the other victims had their legs cut below it. After cutting their legs off, he would bore a hole in the tibias inside of their stumps and the foreign legs to insert a prosthetic attachment that would allow the knee joints to move. He initially dumped the victims after amputating their legs, but later evolved to reattaching a foreign leg onto the stump before dumping them. Due to his inexperience and refusal to accept the laws of biology, some of the victims would slowly die of exsanguination or gangrene as a result of the leg removal or amputation. His ultimate goal was to transplant a foreign leg onto an amputated limb in an attempt to heal his wife. John initially targeted men for his human trials, but then switched to women and amputated their left legs when he felt that he was getting closer to achieving a successful result.
His dump site seemed to change with each victim in accordance to if they survived or not. Hubbel, who didn't survive his surgery, was dumped in Juarez, Mexico, as a forensic countermeasure; Anders survived his surgery and was left in a motel room; Timmons survived his surgery and was left a block away from a hospital, where he later died; and Rodriguez, who also didn't survive her surgery, was dumped in an alleyway. During his attack on Donna Sullivan, he planned to remove her right leg and attach it to his wife's right knee, drugged her when she tried to escape, and attempted to kill her by injecting her with potassium chloride.
The unsub is a male doctor with a severe God complex. His narcissism makes him believe that he can defy human biology and anatomy, and that has likely caused problems in his career. That said, he is probably a doctor who had lost his license or a medical student who had ethical violations. He is not a psychopath, since they rarely have the training and discipline for medical school or residency, so this unsub will not behave in an antisocial matter. He is probably successful, respectful, outgoing, can maintain healthy relationships, and his neighbors probably know him very well. Such a background makes it seem possible that he lives in a mid-to upper-class lifestyle, in which he may be married and have kids; if the latter fact is true, he will be devoted to both. He hides his criminal operations away from his neighbors through a psychological process called "doubling", in which he acts one way professionally and acts another way at home. This unsub's sense of superiority supersedes the Hippocratic Oath.
It was later realized the unsub was a mortician, based on the fact that he had training in cutting and stitching limbs, but never went to medical school and put a biodegradable prosthetic attachment in Carl Timmons' leg. While he may not be a doctor, he may be posing as one around his victims and is operating a bloodmobile to lure them in. The dumping of his latest victim, who is female, means he has another female victim with him and is accelerating his surgeries. He may be a close relative of an amputee, who is working on a solution for his or her loved one's condition. Before he transplant his victims' legs, he turns them into amputees, which is part of his experiment. His loved one may have experienced amputation in utero due to a congenital condition such as rubella or herpes, which would have made one of his or her legs appear amputated. His first three victims were all trial runs, and now that he has operated on women, he thinks he has found a solution.
John amputating his victims' legs and his second fatal victim dying of gangrene as a result is based on the case of John Ronald Brown, who amputated a woman's leg (though the amputation in this case was voluntary), despite not having a medical license to do so, and the victim subsequently died of gangrene.
- October 15: Richard Hubbel (his right leg was removed; died from subsequent exsanguination; his body was found almost five days later)
- October 21: Tony Anders (abducted and non-fatally removed his right leg; was released the next day)
- October 22: Carl Timmons (his right leg was removed and replaced with Tony Anders's; was released, but died of gangrene at a hospital)
- October 23:
- Maria Rodriguez (her left leg was removed and replaced with Donna Sullivan's; died from subsequent exsanguination)
- Donna Sullivan (abducted, removed her left leg, and replaced it with Maria Rodriguez's, then drugged and threatened to kill with potassium chloride; was rescued the next day)