Los Angeles (CNN) -- A death row inmate told relatives and a criminal profiler he killed Nicole Brown Simpson and Ronald Goldman while O.J. Simpson waited nearby, a new documentary claims.

O.J. Simpson was tried and acquitted in the June 12, 1994, stabbing deaths of his ex-wife and her friend, although the actor and football legend was found liable in a civil wrongful death trial.

Glen Rogers, who has been sentenced to death for murdering women in Florida and California, was arrested in November 1995 -- a month after Simpson's murder trial ended -- and charged with killing five women in several states. He told investigators at the time that he had killed at least 70 women, police said.

"I'm absolutely certain that my brother Glen killed Nicole Simpson and Ron Goldman," said Clay Rogers, who narrated the film "My Brother The Serial Killer," which will debut on the Investigation Discovery channel Wednesday. "I know my brother did it because I've seen proof that he was there."

Fred Goldman, the father of Ronald Goldman, immediately rejected the film's contention.

"The overwhelming evidence at the criminal trial proved that one, and only one, person murdered Nicole Brown Simpson and Ronald Goldman," Goldman said in a statement to CNN. "That person is O.J. Simpson and not Glen Rogers."

"The fact that O.J. Simpson was acquitted was a travesty of justice that tarnished the criminal justice system," he said. "Now every guilty person prays to the altar of O.J. Simpson for deliverance from their crimes. A [hundred thousand] screaming Glen Rogers, packed in the Los Angeles Coliseum, all confessing in unison, would not absolve O.J. Simpson of the murders he committed."

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Ronald Goldman's sister lashed out at the Investigation Discovery channel and film producers.
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