David Fincher's new Netflix drama Mindhunter has won plaudits for its skilful blend of fact and fiction. Loosely based on a memoir by the pioneering criminal profiler John E Douglas, many of its characters have real-life parallels under another name.
The show's hero - a young, ambitious FBI agent called Holden Ford - is a stand-in for Douglas, while Ford's senior partner Bill Tench is inspired by Douglas's mentor, Robert Ressler. But one name hasn't been altered: Ed Kemper, nicknamed the "co-ed killer", is entirely real, and still imprisoned to this day at the California Medical Facility.
Mindhunter's depiction of him is eerily true to life. Unlike the other killers Ford and Tench meet, Kemper is polite, eloquent and popular with the prison guards. At one point, Ford even shares a pizza with him. It is his very approachability that makes him so unnerving: it's that same quality that helped real-life Kemper, 6ft 9in and heavily-built, to present himself as unthreatening to the female hitch-hikers who became his victims.
Cameron Britton, the actor who plays Kemper in Mindhunter, is a dead ringer for the killer, with his slightly plump face, unflattering moustache and outwardly gentle manner. What's more disturbing is that some of the fictionalised Kemper's lines are taken from recordings of interviews with the real killer.
At one point in the show, a detective who knew Kemper before his arrest calls him "a friendly nuisance" - a phrase the killer used himself, though the real-life Kemper used this harmless persona as a kind of disguise. He would spend the evenings drinking with police officers from the department responsible for hunting the "co-ed killer", pestering them for information about the case. As he once put it, "friendly nuisances are dismissed."
Born in California, at the age of 15, Edmund Kemper murdered both his grandparents after a petty row with his grandmother (he later claimed he only killed his grandfather to save him from the pain of learning about her death).
He was incarcerated at Atascadero State Hospital, a California institute for the criminally insane, where he proved to be such a well-behaved prisoner that he was trusted to help with carrying out psychiatric assessments on the other inmates.
It's possible this experience helped him to pass his own tests with flying colours, though it's worth noting that he apparently had an IQ of 145. The last doctors' report written about Kemper at Atascadero described him as "a very well adjusted young man", adding "I would see no psychiatric reason to consider him to be of any danger to himself or to any member of society".
He was released on parole in 1969, aged 21. Just three years later, he had begun a new murder spree, beginning with six female students whom he picked up as hitch-hikers. Kemper would decapitate his victims before sexually abusing their corpses. He later described these killings as a kind of "displacement" - a substitute for the one woman he genuinely wanted to kill, but felt unable to: his mother, Clarnell.
In April 1973, he killed Clarnell in her sleep, before using her severed head as a dartboard. Soon afterwards, he handed himself in to the police, a choice he later described as "almost a cathartic process".
Impressive though Britton's portrayal is, it exaggerates his unhurried speech, lacing his pauses with an undercurrent of menace. The real Kemper, it seems, is an even more talented actor; he is almost preturnaturally affable and sympathetic on camera, so long as you don't listen to the actual content of his words. Describing his own crimes, he sounds mildly appalled, as if recalling a distressing newspaper article he once read.
A scene in Mindhunter where Ford and Tench question him about his mother draws on Kemper's actual words from a 1984 interview. But in the interview, he comes across as earnest and repentant.
"I still love my mother," he says, welling up with tears, before regretting the lives that would have been saved if only he had turned himself in sooner: "Those people - not things, those people - would still be with their families, with their loved ones... if I had had the courage to make the decision."
If it's a performance, it is a convincing one leant credibility by Kemper's smooth, reassuring voice. It's a voice that he spent many hours honing; for years, he helped to run a project in which prisoners recorded audiobooks for the blind. He recorded more than 5,000 hours of audio, including a novelisation of the original Star Wars trilogy.
"I can't begin to tell you what this has meant to me," he told the Los Angeles Times in 1987, "to be able to do something constructive for someone else, to be appreciated by so many people, the good feeling it gives me after what I have done."
Like his audiobooks, it seems Kemper took pride in his FBI interviews. At a time when the phrase "serial killer" was still new terminology, Kemper's articulate, self-aware account of his own behaviour was an invaluable resource to the FBI's fledgeling Behavioural Science Unit.
After he was found guilty in 1973, Kemper had requested the death penalty, but was instead given seven concurrent sentences of seven years to life (the most severe punishment available at the time, short of a death sentence).
At first he resented the outcome, but by the time of a 1991 interview he had apparently changed his mind, presenting himself as proud to have been of service to the FBI.
"If I were to have been executed in a timely fashion, they would have had absolutely no input, and would still be scratching their heads about what makes a serial murderer tick."
Serial killers have never been out of fashion, but from The Fall to Hannibal via season one of True Detective and bonkers BBC thriller Rellik, television has lately done an especially roaring trade in manic murderers. Every modern example of the genre carries in its bloodstream the DNA of Se7en and Zodiac, David Fincher’s poised and masterful contributions to the canon.