Edmund Kemper

A major presence in Season 1, Ed reappears in Episode 5 this season to give the agents advice for their Manson interview and for the B.T.K. investigation — particularly on the subject of souvenirs, on which Kemper was an expert. Known in the press as the “Coed Killer,” he killed his grandparents at age 15, served six years in a mental facility, and went on to kill eight women, including five college students; he removed their body parts for post-mortem sex acts.

After killing his mother on Good Friday in 1973, he called the police to turn himself in and was sentenced to multiple life sentences. He has been denied or waived his right to parole hearings several times, and he was most recently denied in 2017, not long after the debut of “Mindhunter.” Kemper will not be eligible again until 2024.

David Berkowitz

B.T.K.’s professed admiration for David Berkowitz, better known as “Son of Sam,” leads the agents to interview him in Episode 2, where they get him to recant his claims of being controlled by a demon-posessed dog.

Demons or not, he cast a spell of fear and paranoia over New York City in the mid-1970s, thanks in part to his frequent communications with local media. Initially called the “.44 Caliber Killer” (after his weapon of choice), Berkowitz killed six people and wounded seven more, his victims mostly women and young couples parked in cars. He was finally apprehended by the New York police in August 1977 and sentenced to 25 years to life for each of his six victims.

In prison, Berkowitz proclaimed himself a born-again Christian, and before his first parole hearing in 2002, he wrote to Governor George Pataki, “In all honesty I believe that I deserve to be in prison for the rest of my life.” He remains behind bars, calling his work as a “caregiver” there to be his “life’s calling.”

Paul Bateson

Interviewed by Carr and Agent Gregg Smith (Joe Tuttle) in Episode 6, Paul Bateson has a particularly twisty history. New York police arrested him in September 1977 in connection with the murder of Addison Verrill , a film reporter for “Variety”; he confessed to the crime in a phone call to the Village Voice columnist Arthur Bell, who reported on the city’s gay scene. When he was convicted in 1979, prosecutors said Bateson had boasted of killing several other men he had picked up in local gay bars — a series of grisly slayings also tracked in Bell’s column.