Charles Manson

Charles Manson (Getty Images)

LOS ANGELES -- A local radio DJ is claiming that notorious killer Charles Manson is his biological father.

Matthew Roberts was adopted as an infant and was raised in Rockfort, Illinois.

Years later, when he went looking for his birth parents, he allegedly discovered a horrible secret.

The 41-year old Roberts says his biological father turned out to be convicted killer Charles Manson.

In an interview with The Sun, Roberts claims his biological mother, Terry, revealed that she had been raped by Manson in a drug-fueled orgy back in 1967.

After his birth, his young mother gave him up for adoption.

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"I didn't want to believe it. I was frightened and angry. It's like finding out that Adolf Hitler is your father. I'm a peaceful person -- trapped in the face of a monster," Roberts told The Sun .

Roberts says he has confirmed his mother's story through letters with Manson, The Sun reported.

"He sends me weird stuff and always signs it with his swastika. At first I was stunned and depressed. I wasn't able to speak for a day. I remember not being able to eat."

Manson is serving a life sentence in the Tate/La Bianca murders.