(CBS) – It was 1957 when 7-year-old Maria Ridulph was killed in far west suburban Sycamore, Ill.

Now the man convicted in her death says he is innocent, and he’s speaking out from prison.

On Dec. 3, 1957, Sycamore had its first snow fall and Maria Ridulph rushed out to play with her best friend. Kathy Sigman was eight.”

“There was a person that came up to both of us and told us his name was Johnny and would we like a piggyback ride?” she tells Erin Moriarty of “48 Hours.”

“After Maria disappeared, my parents said, ‘You are the only one that can recognize this man. You have to remember what he looks like ‘til we find him,’” Sigman says.

Maria’s body was discovered five months later, in a wooded area near Galena, 90 miles from Sycamore. Even with the FBI on the case, Maria’s killer was never found.

Then — a break in the case. Fifty-four years after the crime, 72-year-old Jack McCullough was arrested for the murder. He gave “48 Hours” his only television interview.

Asked if he was the “Johnny” who kidnapped and killed Maria Ridulph, he answers flatly: “Absolutely not.”

But murder wasn’t the only charge McCullough faced. He was also accused of raping his sister, Jeanne, when she was 14.

“Did you abuse your sister, as she was growing up?” Moriarty asked him.

“My sister and I were very close,” said McCullough, who refused to answer any more questions about his sibling.

McCullough was convicted of murder and sentenced to life in prison. He is currently at Menard Correctional Center in Southern Illinois.

Additional portions of the interview air Saturday on CBS.

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