New Jersey Storm owner Jayson Williams faces additional charges in the shooting death of a limo driver last month, the new allegations stemming from what a prosecutor has called a "concerted cover-up."

Williams today was charged with conspiracy to obstruct justice, witness tampering, evidence tampering and hindering apprehension. He had previously been charged with reckless manslaughter following the death of Costas Christofi at Williams' estate in Alexandria Township, NJ.

Christofi was killed when a shotgun Williams was carrying discharged while he gave Christofi and other guests a tour of his home in the early hours of 14 February.

The latest charges against Williams, though, arise from his actions after Christofi had died.

"Our investigation has led us to conclude that Mr. Williams engaged in a concerted cover-up after the shooting," acting Hunterdon County prosecutor Steven Lember said today.

Prosecutors allege that following the shooting, Williams attempted to wipe his own fingerprints off the .12-gauge shotgun, then tried to plant Christofi's fingerprints on the gun.

Williams also moved the gun so that it appeared Christofi's wounds were self-inflicted, affidavits claim, and asked guests to tell police that everyone had been in a downstairs room at the time of the shooting.

Christofi was found dead in an upstairs room in the house.

Courts papers also accuse Williams of disposing his bloody clothes. Williams allegedly told Kent Culuko, a former teammate with the NBA's New Jersey Nets, to dispose of his clothes. John W. Gordnick, however, apparently carried out the act of removing the clothes, but has since turned them over to authorities.

Culuko and Gordnick were charged today with evidence tampering, hindering apprehension and conspiracy to obstruct the law. Culuko was also charged with witness tampering.

The charges against Williams will now be sent to a grand jury for a possible indictment for aggravated manslaughter rather than reckless manslaughter. The upgraded charge requires proof of "extreme indifference to human life." An aggravated manslaughter conviction carries a sentence of up to 30 years in prison.