LOS ANGELES -- O.J. Simpson pauses from describing the moments before his ex-wife Nicole Brown Simpson and her friend Ronald Goldman were murdered. He shakes his head and looks away from the camera, bringing a hand up to his forehead.
"I really can't do more of this," he says, repeatedly, as he approaches the more gruesome details of what happened that night.
Simpson was speaking to Judith Regan in a 2006 interview that Fox said was "lost" on the network's lot and will be the subject of the Fox special "O.J. Simpson: The Lost Confession?"
During the discussion, Simpson gives what the network describes as a "hypothetical account" and "disturbing" details about the night of the slayings.
Fox hosted a screening of the 45-minute-long interview portion of the special for the press Thursday. The program will air Sunday, against ABC's reboot of "American Idol."
The special, hosted by Soledad O'Brien, will include input by a panel of analysts, including Chris Darden, one of Simpson's prosecutors in his criminal trial. Public service announcements about domestic violence awareness will run throughout the program.
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Regan begins the 2006 interview by asking about Simpson's book "If I Did It," which Simpson said he wrote primarily for financial reasons, because his National Football League pension wasn't enough to cover his expenses.
Several times throughout the interview, he described Brown Simpson -- she was insecure about her weight, wore tight dresses, got plastic surgeries and was a confrontational person, he said.
Simpson remained conversational, without much reserve throughout the interview, but when the topic of discussion neared the night his ex-wife was brutally murdered, Simpson's demeanor shifted, his responses became terse, and refused to answer some questions.
"I prefer you read the book" for those parts, he said.