|“||It's time to go. Leland is waiting for us down there. It's time we join him.||”|
— Jess to Timmy Kane
"I came back to the lake to make it right... to add to the treasure. And then-and then, I found you. A fellow pirate. Leland's going to forgive me now."
Growing up in Ramona, California, Jess regularly played pirates with his friends, including another boy named Leland Turner whom Jess was especially close to. On one occasion, Jess assaulted another student at school while Leland and another friend cheered him on until police arrived and arrested both boys. In their games, the two and others committed petty crimes, resulting in them having long juvenile records, including petty theft and truancy. However, Leland and Jess took their pirate game a step further by swearing a blood vow, which involved them cutting their hands with a heated blade and holding them together while reciting the Pirate's Code, allowing their mixed blood to drip on a Jolly Roger flag. Leland's home was situated in Palmer Canyon outside Ramona, where the pair had a hiding place for a box containing various trinkets that they considered their "treasure". In 1997, there were plans to create a reservoir and Leland was among the residents forced to vacate their homes so the canyon could be flooded. Despite knowing the danger in going into the canyon, Leland insisted on "defending the treasure". Jess, however, was too afraid to join him and remained at home. That day, plans to create the reservoir went ahead and Leland was killed in the ensuing floods.
After Leland's death, a guilt-ridden Jess, believing he had broken their oath, descended into a downward spiral. He became extremely violent and on August 18, police were called to his home after multiple neighbors reported screaming and fighting throughout the night. His parents John and Claire, unable to control their son, surrendered custody, making him a ward of the state. Finally, on February 24, 1999, Jess was institutionalized out of state and put on antidepressants. Being medicated and isolated during his formative years left Jess in a state of arrested development. By the time he was twenty-four, Jess had been released and moved to San Diego, California, where he worked as a handyman and part-time janitor for a time. In 2017, Ramona suffered a severe drought, causing the water levels of the reservoir, Lake Palmer, to decrease and the skeletons of those who died on the lake following its creation started to be recovered from the depths. When Jess learned of this, he abruptly quit his job and returned to Ramona under the delusion that he was a pirate who had come back to Lake Palmer to add to the treasure buried by him and his partner years ago. He began killing residents with pools in their backyards and afterwards stole items from their home to offer to Leland as treasure, beginning with Ben Stiles following the discovery of the first body on November 22, also stealing his coin collection from his home. On November 28, when another set of remains was found, Jess struck again, drowning Bert Schofield the next day and making off with his bowling trophies.
Following the recovery of two more bodies from Lake Palmer, Jess attacks newlywed couple Larry and Wanda Robbins, quickly shooting Wanda and pushing Larry into the pool while tied to a cinder block. After killing them, he ransacks their house and steals costume jewelry belonging to Wanda. Their deaths lead to the BAU being called in to investigate the murders. The following day, Jess returns to his hideout in an old shed next to Lake Palmer. He briefly looks at his reflection in a mirror before pouring bleach over his right eye while screaming in agony as his face burns. Later, he scatters the coins from Ben Stiles's collection along the shores, which are soon discovered by Bob Turner, Leland's father who had returned to Ramona to search for his son, and watches as authorities recover another victim from the lake. As Jess, now badly burned around his eye from the bleach, observes the retrieval through a pair of binoculars, he is discovered by a wandering boy named Timothy Kane, who asks what happened to his eye. Jess turns away from Tim, trying to hide the damage to his face, as the pre-teenage boy inquires if Jess is living in the shed and introduces himself. Approaching Jess, Tim tells him about the latest body and Jess responds by asking what the body looked like, wondering if it might be Leland. Tim answers that it was in a bag and asks Jess if he believes in ghosts. Jess nods affirmatively. Later, Jess invites Tim to his shed, where Tim is impressed by his collection of pirate memorabilia. He notices the blood on his Jolly Roger flag, to which Jess recounts the blood oath he made with Leland and asks if Tim wants to make the oath. When he tells Tim he has to prove himself by spending a night on the lake, Tim, worried that his parents will be angry, tries to back out, but Jess pressures him by asking whether if he is a pirate or a scared little boy. Tim accepts his challenge and succeeds, delighting Jess. The two perform the blood oath, which causes Jess to remember his past and tell Tim about Leland and what happened to him. Tim tries to leave, but Jess refuses to let him go, convinced that the two of them need to join Leland at the bottom of the lake so his soul can rest. He takes a tied-up Tim out to the docks with plans to drown the both of them, but Simmons arrives after the BAU is alerted to Tim’s disappearance while investigating Jess’s murders. Jess shoots at Simmons before tossing Tim overboard and driving the boat away, forcing Simmons to let him escape in order to rescue Tim. Later, the BAU is informed by Sheriff Mason that Jess’s boat was found abandoned in the middle of the lake, to which Rossi realizes that Jess had committed suicide by sending himself to the bottom of the lake, finally honoring his blood oath with Leland.
Jess targeted homeowners in Ramona who had swimming pools in their backyard. More specifically, he chose homeowners whose pools had diving boards that he could use to make his victims walk the plank, a method of execution used by pirates. Jess would ambush them in their backyards and apparently subdue them with a weapon then bind their hands and legs with rope. After tying their ankles to a cinder block to ensure that they drowned, Jess would force the victims to carry it as they walked his plank to a watery demise. In the case of Larry Robbins, Jess pushed him into the pool, sewn into a bedsheet while tied to a wrought-iron chair. When confronting the Robbinses, Jess quickly shot Wanda in the chest, killing her instantly and proceeded to kill Larry using his usual methodology. After killing the victims, Jess would loot their homes for valuables; stealing a coin collection, bowling trophies and costume jewelry, respectively. The items taken would be of low monetary value but would easily be considered valuable by pirates due to their shiny appearance and served as his additions to the treasure buried by himself and Leland before the latter's death. Sometime after stealing them, Jess would leave the items along the shore of the lake as an offering to Leland.
The unsub is a mission-oriented killer who is targeting residents in Ramona with backyard pools. The sole female victim, Wanda Robbins, was found partially nude yet wasn't sexually assaulted and was killed quickly with a single gunshot while the male victims are forced through prolonged, agonizing deaths instead of simply shooting them as well. This indicates that they are the unsub's true targets. Originally, the BAU suspected that the burglaries following the murders were merely a forensic countermeasure because the items stolen were of such low-value and were so specific. Although he kills in Ramona, the unsub traveled miles to dispose of Ben Stiles's coin collection along the shores of Lake Palmer. Because of this, he may work or even live at Lake Palmer. The crime scenes show signs of struggle yet there are no corresponding defensive wounds on the victims so the unsub may have ransacked the homes after killing the victims purely for excitement, meaning he is full of rage. There is a disconnect with this unsub; on the one hand, the crime scenes are extremely organized, suggesting a killer with maturity and skill. But then he steals bright, shiny items of little monetary value, suddenly reverting to immature and impulsive behavior. This means he is likely in a state of arrested development and the thefts themselves may be symbolic. Wrapping a body in a bedsheet would normally be a sign of remorse on the part of the unsub, however, the fact that Walter Knight had a needle stuck through his nose while he was still alive instead means the level of sadism in his crimes is rising.
The unsub appears to be killing in direct response to the old accident victims being recovered from the lake. The stolen items dumped on the lake's shores may serve as an offering of some kind. It was later deduced that the stolen items weren't afterthoughts but were, in fact, the unsub's true goal. Deaths by drowning, pillage and plunder and the unsub implementing a centuries-old ocean burial tradition that was especially common among pirates also revealed why he selected these specific pools over others; each of the victims' pools has a diving board or, in the unsub's mind, a plank for them to walk on, just like in pirate tales of lore.
- Unspecified date: Unnamed student (assaulted)
- November 23: Ben Stiles (stole his coin collection from his home)
- November 29: Bert Schofield (stole bowling trophies from his garage)
- December 4: Larry and Wanda Robbins (stole some of Wanda's costume jewelery from their home)
- Larry Robbins
- Wanda Robbins (was shot once in the chest and dumped in their pool)
- December 4-5: Walter Knight (wrapped and sewed a bedsheet around him and stuck a needle through his nose; weighed down with a chair instead of a cinder block)
- December 6:
- Timothy "Timmy" Kane (attempted; briefly held captive, tied up and intended to drown with a cinder block, later thrown overboard; was rescued)
- Matthew Simmons (attempted; shot at three times, hit twice but was protected by a bulletproof vest)
- According to his employment history, Jess's social security number is 973-00-0128.
- Although he was referred to as Leland Peters and this name was displayed on Garcia's screen, Jess likely knew him as Leland Turner.
- It was deduced this is how he attacked the Robbins couple and given that there were no signs of forced entry at every crime scene, it's possible he did so with the others as well