A former judge from Long Island was sentenced yesterday to 33 months in prison for conspiring to launder almost $400,000 in proceeds from stolen jewelry.

The ex-judge, David A. Gross, 45, of Nassau County District Court, had pleaded guilty in July to money laundering, and was sentenced in Federal District Court in Central Islip.

Prosecutors said that while the judge was running for re-election in January 2005, a member of the Genovese crime family introduced him to a wealthy businessman. The judge did not know that the “businessman” was an undercover F.B.I. agent.

As part of a sting operation, the agent told the judge about diamonds and watches he had stolen, and the judge agreed to fence them, according to the charges. He said he could use his legal knowledge to avoid detection, and offered to launder cash through his campaign funds.