New York ? Infuriated by reports of an attempted coverup, the family of the limousine driver Jayson Williams allegedly shot dead said Wednesday that it wants him behind bars for as long as possible.

Chris Adams, the nephew of victim Costas Christofi, called the former Nets player a coward.

“He should be put in jail for no less than 10 years  the maximum sentence,” Adams said.

His comments came after a new report charged that Williams  who allegedly blasted Christofi with a shotgun during a tour of his New Jersey mansion  tampered with evidence to make the shooting appear to be a suicide.

The former NBA standout tried to put Christofi’s palm print and fingerprints on the weapon after the shooting, Sports Illustrated quoted a witness as saying in its latest issue.

Williams also discarded the bloody clothes he was wearing, while his brother called 911 and lied to cops  saying the 55-year-old Christofi had killed himself, according to the magazine. Williams, charged with reckless manslaughter, is free on $250,000 bail.