O.J. Simpson killed his ex-wife because she had resumed an affair with football player Marcus Allen, attorney Daniel Petrocelli said in a TV interview.

Petrocelli, who convinced a civil court jury that Simpson was responsible for the deaths of Nicole Brown Simpson and her friend Ron Goldman, told "Dateline NBC" that Simpson could not accept that his ex-wife had rejected him for the Kansas City Chiefs star."Every time I spoke to witnesses close to Simpson, it always came back to Marcus Allen," said Petrocelli, who represented the Goldman family in the wrongful death suit. "I believe that that was what made Simpson snap."

An unidentified spokesman for Allen told "Dateline NBC" that Allen never had an affair with Nicole Simpson and said Petrocelli was "playing fast and loose with the truth."

The interview was broadcast Tuesday night.

Simpson was acquitted of killing Nicole Simpson and Goldman in 1994, but the civil jury last year found him liable and ordered him to pay $33.5 million in damages.

Petrocelli said Nicole Simpson had a history of using Allen to get back at her ex-husband and that Simpson envied Allen, who was playing in the National Football League while Simpson's career was cut short by injury.