John Lee Roche was a convicted child molester and serial murderer arrested by Fox Mulder in 1990. While in prison, he confessed during a polygraph test to thirteen murders. He also cut out heart-shaped mementos from his victims' clothing. In 1996, Mulder had a vivid dream that led him to a fourteenth victim in Manassas, Virginia. Upon discovering a heart-shaped cutout, Mulder knew Roche was responsible and, with Scully, went to visit him in prison. Roche said he confessed to thirteen murders because the number seemed more "magical." After visiting with the victim's father, Frank Sparks, Mulder had a flash of realization as to the whereabouts of Roche's hearts and sought out the current owner of Roche's white El Camino. Sure enough, the hearts were discovered within the pages of Alice in Wonderland - all sixteen of them.
Mulder and Scully returned to Roche demanding to know the identities of the two additional victims. The case became very personal for Mulder, who believed he was developing a psychic connection to Roche and that one of the victims was his sister. Roche agreed to the give the location of one of the victims, who was soon discovered. Mulder was convinced that it was his sister until he realized that the body's left collar bone was not broken like his sister's had been. That left only one heart.
Mulder made some phone calls and arranged to transport Roche to Martha's Vineyard with him to locate Samantha's body. Scully had learned that Roche lived in Boston during the early 1970s and most of his killings were done near where he lived. He also worked as a vacuum salesman for Electrovac and sold a vacuum to William Mulder. On Martha's Vineyard, Roche gave a vividly detailed account of his kidnapping of Samantha, which Mulder realized was all a sham - they were not even in the right house that Roche claimed to have done everything in. Furious, Mulder brought Roche back to the hotel, still in handcuffs.
However, during the night, Mulder experienced another vivid dream and awoke to discover Roche had escaped and that Mulder had been handcuffed to a table. By this time, Scully and Skinner had traveled from Washington and were shocked to find that Mulder had been outmaneuvered by Roche - who had also taken his badge and gun. Mulder knew where Roche would go, however: on the airplane, he had shown interest in a little girl named Caitlin Ross who lived in Boston and planned to relive his past crimes. Mulder led a team to Revere, Massachusetts and discovered Roche and the girl in an abandoned train car.
Roche sat behind the girl with Mulder's gun pointed at her back. Mulder approached Roche with his second pistol, pleading with him to let her go. Scully and Skinner watched the drama unfold with their own weapons drawn as well. Mulder asked Caitlin to count to twenty and demanded that Roche het her go. Roche taunted Mulder that the last remaining heart might very well be that of Samantha, but Mulder had grown tired of Roche's mind games. As Caitlin reached twenty, Mulder shot Roche dead with a bullet to the head at point-blank range.