The FBI banned solo interviews with serial killers after one made terrifying comment to an agent

It's hard to believe that the FBI ever allowed one-on-one interviews with literal serial killers, but things had to change back in the 1980s after a particularly terrifying comment.

Thanks to true crime documentaries and drama series such as Netflix's Mindhunter, many of us are far too familiar with the crimes committed by some of history's worst offenders.

Mindhunter in particular has proven popular, with the show's inspiration John Douglas opening up recently on the chilling way psychopaths are often able to pass polygraph tests and lie detectors.

One of the worst serial killers he studied in the show is Edmund Kemper, known as the 'Co-ed killer' after he brutally murdered eight women including his mother in the space of 11 months, having already killed his grandparents at the age of 15.

The American man was convicted in late 1973, having spent much of the last year picking up hitchhiking young women from high schools and colleges before murdering them and performing sexual acts on their corpses. It is believed that the young women were simply surrogates for his mother, who was his second-to-last victim before he turned himself into police.

A recent photo of the 76-year-old also left fans of the show very creeped out, as at six-foot-nine, he is still a threat to anyone who comes close to him, even though he is now reportedly confined to a wheelchair.

Despite some sources describing Kemper as an almost-model citizen during his time behind bars, he has been repeatedly denied parole over his last 42 years living in the California Medical Facility, and considering what he said to FBI agent Robert Ressler back in the 1980s, it's easy to see why he will never see freedom again.

The photo was taken in June 2024. (Instagram/@thisisedkemper)

According to American researcher and psychiatric clinical nurse specialist Ann Burgess, Kemper told Ressler at the end of one of their interviews: "The guard isn't coming back. They're on change of shift. He's not going to be here for 30 minutes. In that time, I could snap your head and leave it on the table. I'd own the prison then. I killed an FBI agent."

Given the serial killer's apparent affixation with the human head, as he savagely decapitated most of his victims, that was an extremely serious threat, and you wouldn't have blamed Ressler for bolting out of the room as soon as he heard the terrifying statement.

Kemper photographed during his trial. (Bettmann Archive/Getty Images)

After the guard came back, Kemper said he was joking, but the FBI certainly didn't see the funny side, and from then on, all agents were required to conduct interviews in pairs and could no longer do them on their own.

Despite originally requesting the death penalty at his trial in 1973, Kemper is still alive today, and will be up for parole again in 2031.