Originally assigned to assist Special Agent Bill Patterson in apprehending the serial killer John Mostow, Nemhauser was instrumental in halting the criminal's murderous ways. Unfortunately, following the capture of Mostow, the killings continued, forcing Agent Patterson to seek the assistance of Agent Fox Mulder. While Mulder investigated Mostow's studio, he discovered Special Agent Nemhauser's dead body encased in clay. When Patterson arrives at the studio, Mulder accuses him of killing Nemhauser and everyone else murdered since Mostow's incarceration.
Date of Death: Unknown
Eps: "Grotesque" (3X14)

Responding to requests for assistance from the Cleveland police, Agents Scully and Mulder team-up with Detective Alan Cross to investigate a strange murder. The victim, Lauren Mackalvey, was found doused in hydrochloric acid and pepsin, a digestive enzyme. Mulder discovers that Mackalvey had last been seen preparing for a date with an online persona known as "2Shy". Utilizing 2Shy's unique Italian poetry, Dana and Detective Cross are able to form a list of potential suspects who had access to the obscure literature source. While investigating the apartment of Virgil Incanto, a scholar and translator, Detective Alan Cross is is murdered by Incanto.
Date of Death: October 1995
Eps: "2Shy" (3X06)

Special Agent Jeffery Spender

Agent Scully's investigation of Agent Spender's mother, Cassandra Spender (a.k.a. Patient X), revealed a possible history of alien abduction, though he vehemently denies it as a hoax. Irritated with the constant interference of Agents Mulder and Scully in his cases and the investigation of his mother's abduction, Spender has been coerced by offers of assistance from his father, the Cigarette-Smoking Man. Becoming the new FBI informant for the Syndicate, and controlling all X-File investigations, Spender reported all activities to his father. Agent Spender betrays the Syndicate when he learns of their masterplan to overthrow the world... and the part they played in Cassandra's abductions. Unable to control his son any longer, CSM shoots him.
Date of Death: Unknown
Eps: various

Sheriff Andy Taylor

The investigation of the death of a badly deformed newborn bring Mulder and Scully to the eerie town of Home, Pennsylvania. Immediately suspecting the nearby family, whom Sheriff Taylor identifies as the Peacocks, Mulder and Scully investigate the vacant home and discover evidence of the recent birth. Before Mulder and Scully are able to reach Sheriff Taylor with the evidence for a warrant, the Peacocks break into his home and brutally bludgeon him and his wife to death.
Date of Death: Unknown
Eps: "Home" (4X03)