S4E10 · Paper Hearts

Fox Mulder (David Duchovny) dreams of a red light that leads him to the corpse of a young girl buried in a park in Manassas, Virginia. When he awakens, he heads to the park and finds the girl's skeleton. The girl was determined to have been murdered by John Lee Roche (Tom Noonan), a serial killer who murdered thirteen girls throughout the 1980s; his modus operandi included cutting a heart out of the clothes of each victim. Mulder had captured Roche by deducing that he committed the murders while traveling as a vacuum cleaner salesman. Roche's hearts were never found, although he confessed to all of the murders.

Dana Scully 's (Gillian Anderson) autopsy of the skeleton finds that the victim died in 1975, suggesting that Roche's killing spree started much earlier than the FBI had previously thought. The agents search Roche's old car, where they discover sixteen cut-out hearts. Mulder and Scully subsequently visit Roche in prison, hoping to learn the identities of the remaining two victims. Roche, however, tries to play mind games with Mulder. That night Mulder dreams of the night of Samantha 's abduction, seemingly showing that his sister was abducted by Roche rather than aliens.

The next day, Mulder asks Roche where he was the night Samantha was abducted. Roche claims he was on Martha's Vineyard and had sold a vacuum cleaner to Mulder's father. Mulder later finds the vacuum in his mother's house. After convincing Walter Skinner to grant them further access to Roche, the agents question the killer and are told the location of one of his remaining victims. He also claims exactly what happened the night of Samantha's abduction. An autopsy of the body reveals it does not belong to Samantha. Roche tells Mulder the final body is Samantha's, but says that he will only reveal where it is if Mulder takes him to the scene of her abduction. Mulder secretly releases Roche from prison and brings him to Martha's Vineyard.

Upon arriving at his family's old summer house, Roche explains exactly what happened the night of Samantha's abduction. However, Mulder tells him that the house was bought by his father after Samantha's abduction, convincing him that Roche is not telling the truth. Mulder plans to bring Roche back to prison, but—following another dream about Samantha—awakens to find Roche gone, with his badge, gun, and phone stolen.

Using Mulder's credentials, Roche kidnaps a girl in Swampscott, Massachusetts, whom he met on his flight with Mulder to Boston. Scully and Skinner arrive and the agents head to the site of Roche's old apartment in Revere. They find him with the girl in an abandoned bus nearby. Roche holds a gun on the girl and tells Mulder that he'll never know for sure whether the last victim is Samantha or not if he kills him. As Roche starts to pull the trigger, Mulder shoots him dead. In his office, Mulder stares at the final cloth heart and puts it away, unsure of whether it belonged to Samantha or not.