|“||He begged me not to hurt you. To let you go because you're a wonderful person, he said. So I tried to feel what he felt for you but to be honest...I didn't feel a thing.||”|
— DuFour to Sarah Miles
Ever since he was a teenager, Jacob was showing signs of severe mental illness. He would remove the heads and furs of animals and wear them, and also expressed his wonder on what it would be like to live in someone else's skin. On October 6, 1992, Jacob was arrested for animal cruelty after a neighbor complained about him dancing around with a bloody animal pelt fastened to his head as a hat. He had been repeatedly institutionalized in psychiatric hospitals since then. At some point prior to "Internal Affairs", he inherited the Diablo General Store, a general store in Esperanzo Valley that had been owned by his family for sixty years. In 2011, Jacob began killing, taking advantage of clashes between drug cartels along the U.S.-Mexico border to cover up the true nature of his murders.
An investigation into his serial killings was started in Ciudad Juárez, Mexico, by a police detective named Santiago Morales, who sent a report of it to the El Paso Police Department in case there were any similar victims in the U.S. Morales later died on June 26, 2014, of a brain tumor and no one followed up on the investigation, leaving it cold. On December 2, 2014, Morales's report was seen by Brian Cochran, who requisitioned it. He later decided to take advantage of it by sending potential victims to Jacob when he saw them as loose ends to the Libertad Cartel, a rising drug cartel he was affiliated with. This led to the death of DEA Agent Mark Bowers, who was working undercover to find the leader of the Libertad Cartel.
Jacob is first seen entering the shed holding a jug of water and iodized salt. In the shed are his latest captives, DEA Agents Sarah Miles and John Portman. Sarah asks him who he is, what he wants with them, and why they are in the shed, but he doesn't respond. As she asks, Jacob pours the salt into the jug of water, mixes it, and forcibly pours it down into John's throat, then leaves. He later returns to the shed and Sarah again asks him what he wants with them, but he still doesn't respond. When Jacob approaches Sarah, he touches her cheeks. While he does, John tells Jacob to leave her alone. In response, he approaches John, removes the chain, and drags him out of the shed. The following night, Jacob returns to the shed, disguising himself as John using his removed face. He taunts Sarah and throws John's face to the ground, horrifying her. Jacob then tells Sarah about how John begged him not to hurt her and to let her go. Then, he says that he tried to feel what John felt for her by putting on his face, but remarks that he didn't feel a thing.
The next day, as Jacob takes off his gloves, he sees through his smartphone that Morgan and Lewis have arrive at the general store. Deciding to abduct one of them, Jacob tells Sarah that she is about to have some company, then takes the taser and leaves the shed as Sarah cries. When Lewis approaches Jacob's house, he appears, lowers Lewis' guard by pretending to be developmentally disabled, and asks her if he can help her. Lewis asks him if he lives in the house, and he replies that he does. Jacob then introduces himself, and when Lewis extends her hand to shake his, he instead stuns her with the taser. Then, Morgan appears, fires a warning shot at Jacob, and pursues him as he flees. After a short chase, Morgan pursues him to Jacob's car, where he takes out a shotgun and fires at him but misses. When Jacob empties the shotgun and tries reloading it, Morgan shoots at Jacob and kills him. Afterward, Lewis, recovering from the stun, finds Sarah in the shed as the latter begins sobbing hysterically.
"You're about to get some company."
Jacob targeted people during the violent clashes between drug cartels. Initially, he targeted random Hispanic people in Mexico but later started receiving his victims from Cochran, who would be brought to him after they took the local bus number 8 to the last stop at Diablo General Store in Esperanza Valley, thinking they were having another meeting with Jillian Carter. After they arrived, he would somehow abduct them (likely by using a ruse and then incapacitating them with a taser, like he did with Lewis), hold them captive by chaining them inside a shed on his property, torture them with dehydration and electroshock, and kill them by strangling them with his bare hands. His signatures were crudely removing their faces for his own use, and also placing the removed face of a previous victim over their own faces (done via surgically implanted attachments) post-mortem. Then, he would dump them near mass graves or dumping sites used by local drug cartels except for Agent John Portman, whose body was simply dumped in a desert in El Paso.
The unsub is an American male serial killer who is trying to hide his crimes amid drug violence. His most recent victims were all undercover DEA agents who were investigating the Libertad Cartel. His post-mortem removal of his victims' faces requires patience and diligence, which suggests he is aged in his mid-thirties or possibly even older. He may have a history of mental illness as well as hunting skills, based on the dissection of his victims' faces. He likely had victims prior to the known killings and those victims were hidden among the numerous drug cartel targets. It is possible he is a member of the Libertad Cartel, since anyone can join it, or someone within the cartel is aware of the unsub's activities and has been sending him new victims as a forensic countermeasure.
The fact that Jacob took advantage of clashes between drug cartels to hide his crimes seems to be based on the assumption that the Juárez Ripper(s), a Mexican serial killer(s), was/were committing several murders in Ciudad Juárez and pinning them on organized crime and drug cartels.
Jacob is also partially similar to Richard Chase, who was a mentally-ill serial killer who also killed animals as a minor and mutilated his victims post-mortem to satisfy some sort of delusion. His habit of removing and wearing his victims' faces seems to be based on Ed Gein's M.O., as he also removed the face of his victims post-mortem, and made masks from the skin of the heads of his female victims and wore them.
- 2011, Ciudad Juárez, Mexico:
- May 6 (found): R. Ricardo (full first name unrevealed; dumped his body by the Sinaloa Cartel's dumping ground)
- July 19 (found): S. Garagos (full first name unrevealed; dumped his body by the Juárez Cartel's dumping ground)
- September 17 (found): N. Degas (full first name unrevealed; dumped his body by one of the Gulf Cartel's dumping grounds)
- January 8, 2012, Ciudad Juárez, Mexico (found): E. Vargas (full first name unrevealed; dumped his body by one of the Gulf Cartel's dumping grounds like the previous victim)
- Unspecified dates from 2012 to 2015, the U.S. and/or Mexico: Numerous unnamed victims
- 2015, El Paso, Texas, U.S.:
- November 12: Agent Mark Bowers (abducted; later killed on November 27-28; attached Arvin Cole's face over his own face post-mortem and dumped his body by the Sinaloa Cartel's dumping ground)
- November 26: Agent John Portman (abducted; later killed on December 3 and then removed his face post-mortem like the below victim)
- November 28: Arvin Cole (abducted; later killed on an unspecified date and then removed his face post-mortem; his body was never found)
- December 2: Agent Sarah Miles (abducted; was rescued two days later)
- December 4: The general store shootout:
- Jacob is based on a few other unsubs on the show:
- Season Five serial killer Ronald Boyd. Both were prolific serial killers who operated near the U.S.-Mexico border, took advantage of the activities of local drug cartels to mask the true nature of their murders, killed two people working in law enforcement, and attempted to kill a member of the BAU by shooting at them with a long gun, before being killed themselves by Morgan.
- Season Three budding serial killer Max Poole. Both were killers and abductors who operated in Texas (although Jacob also killed victims in Mexico), removed their victims' faces (although Jacob did it post-mortem, while Max did it ante-mortem to kill them), and attempted to kill Morgan by shooting him before being shot and killed.
- Season Ten serial killer Jerry Tidwell. Both were prolific, psychotic serial killers and abductors who were institutionalized as teenagers, had inherited businesses from family members after their deaths, operated in multiple countries (one of which was the U.S.), killed their victims by strangulation, and were shot and killed after attempting to shoot and kill at least one member of the BAU.
- Jacob's habit of wearing the removed faces of his victims seems to be inspired from Leatherface, the iconic antagonist of The Texas Chainsaw Massacre slasher film franchise.