IN a blockbuster new book, crooner Andy Williams defends ex-wife Claudine Longet for her role in an infamous homicide more than 30 years ago.

The French-born singer/actress was charged with killing her lover, Olympic skier Vladimir "Spider" Sabich, in their Aspen, Colo., home in March 1976.

Williams had divorced Longet a year before the shooting, but he was at her side throughout the trial.

A publishing source familiar with his upcoming memoir Moon River and Me tells The ENQUIRER that the 81-year-old singer still seems obsessed with the horrific event.

Andy writes about the incident in depth, and provides new details, the source told The ENQUIRER. The singer makes a methodical attempt to debunk much of the evidence presented by prosecutors at the sensational trial.

"Andy also says that Claudine’s confiscated diary did not contain confessions of frequent drink- and drug-fueled arguments between her and Spider, and that police blood tests showing her to have traces of cocaine in her system were false," said the publishing source.

"Andy also calls the rumors false that Spider was tired of Claudine and was trying to dump her and had a $100 bet that she’d soon be out of his life."

Longet, who claimed the shooting was accidental, was found guilty of criminally negligent homicide. She received only 30 days in jail, and married her defense attorney a decade later.

In the book – due to be published Oct. 13 – Williams also denies a long-held belief that he carried on a romance with Ethel Kennedy after her husband Bobby was assassinated in 1968.

Williams campaigned for Kennedy before his assassination, and escorted Ethel to numerous events in the ’70s. The singer has been married to second wife Debbie Haas since 1991.

"Andy puts the rumor of a romance between him and Ethel to rest," said the source.

"He writes he was always happy to be with her, but never harbored the thought of taking Bobby’s place in her heart."

A persistent rumor states that Andy, while a teenager, provided the dubbed singing voice of Lauren Bacall for her song "How Little We Know" in To Have and Have Not (1944). Bacall herself addressed it in her autobiography, stating that Williams did dub a couple of high notes for her, not the whole song.