New York police who killed an unarmed black man with 50 shots on his wedding day were careless and desperate to make an arrest because their vice unit was about to be disbanded, a prosecutor said on Monday.

Two officers went on trial for manslaughter and a third for reckless endangerment in the death of Sean Bell, 23, who was killed in 2006 following a bachelor party at a strip club in a case generating outrage in much of New York's black community.

Civil rights activist Al Sharpton sat next to the fiance, Nicole Paultre, in a gallery packed with friends and relatives of the victim and police sympathetic to the defendants. Protesters outside, many of whom wanted murder charges against the officers, held up signs numbered 1 to 50, chanting each number.