New York (CNN) -- Former pro basketball star Jayson Williams was sentenced to an additional year in prison Friday after he pleaded guilty to a misdemeanor charge of driving while intoxicated, according to the Manhattan district attorney's office.

Williams had a blood-alcohol level of more than twice the legal limit when he crashed his Mercedes into a tree in lower Manhattan in January -- just a week before he pleaded guilty to aggravated assault for accidentally shooting and killing a limousine driver in New Jersey, the district attorney's office told CNN.

The year will be added on to the current five-year prison sentence the former NBA player is serving in state prison in New Jersey. He also was also slapped with a $16,433 fine to repair the tree he hit.

Williams had been sentenced to five years in prison after fatally shooting his limo driver, Costas "Gus" Christofi, in February 2002 at his New Jersey estate. Christofi had been hired to drive the former athlete and several of his friends to dinner after a sporting event in Pennsylvania.

The group, including four members of the Harlem Globetrotters, later went back to Williams' home. The prosecution argued that Williams was recklessly handling a 12-gauge shotgun when it discharged and that he and two others tried to make it look as if Christofi had shot himself.

Williams, who retired from the NBA in 1999 because of a leg injury, played nine seasons with the Philadelphia 76ers and the New Jersey Nets.