Ed Kemper got involved with recording audiobooks during his time in prison at California Medical Facility.

While you may have gotten used to the voice of the actor who plays serial killer Ed Kemper in the super addictive “Mindhunter” series, you may have also been exposed to the real killer’s voice while listening to your favorite classic audiobook if you’re old enough to have listened to it on tape.

That’s right: The man who murdered his own grandparents, his mother, and numerous co-eds is the same voice behind numerous audiobooks.

A 1987 article from the Los Angeles Times reported that he led an audiobook project, Volunteers of Vacaville, from behind bars. He and his fellow inmates recorded thousands of audiobooks, and Kemper personally recorded hundreds of them.

“Two large trophies saluting Kemper for his dedication to the program, presented by supporters outside the prison, are on display in the Volunteers prison office, which has eight recording booths, two monitor booths and a battery of sophisticated tape duplication equipment,” the article stated.

Photo: Netflix, Getty Images

According to an archived version of Volunteers of Vacaville’s website, among the books Kemper voiced were "Star Wars," "The Rosary Murders," and "Flowers in the Attic.”

In fact, you can listen to the killer reading an excerpt of “Flowers in the Attic” complete with whoever uploaded it snickering after Kemper reads the line, “Goodbye, Daddy.” That book deals with incest and family abuse, something not unfamiliar to Kemper.

Kemper had killed his own grandparents when he was just a teen. He was let out on parole on his 21st birthday and then went on to kill eight more people, a murder spree which ended with the killing and decapitation of his own mother, before having sex with her body.

Kemper discussed much of these crimes at length on “Mindhunter” in between chummy chats with FBI agents and pizza slices.

Volunteers of Vacaville still exists at California Medical Facility, where Kemper is incarcerated, though now it seems more focused on Braille transcription than audiobooks. It’s not clear if Kemper is still involved with the non-profit. He retired from the role in 2015 after suffering a stroke, according to parole hearing paperwork.

Back in the late ‘80s, he seemed very proud of his work.

“I can’t begin to tell you what this has meant to me, 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,” he told the Los Angeles Times.