NEW YORK (AP) – The grand jury met for more than three months. It analyzed hundreds of pieces of evidence, from maps and hospital records to videotapes and toxicology reports, before indicting three officers involved in a 50-bullet barrage that killed an unarmed man on his wedding day.

But the explosive case is just getting started, lawyers said Saturday.

The indictment is just one small first step in a process that will drag on for months and likely produce an emotional, difficult trial. And proving criminal charges against on-duty officers may be no easy task.

“The grand jurors needed to jump a 2-foot hurdle,” said attorney Philip Karasyk, who represents one of the indicted officers, Gescard Isnora. “At trial, the jury needs to jump a 10-foot-high hurdle.”

A grand jury deliberated for about three days before deciding that three police officers deserve to be prosecuted in the death of Sean Bell, 23, who was shot while leaving a bachelor party at a Queens nightclub.

The ill-fated groom was being followed by plainclothes police detectives who thought someone in his party had a gun. Five opened fire after one undercover officer thought he glimpsed a weapon. Bell died and two of his friends, Trent Benefield, 23, and Joseph Guzman, 31, were wounded.

In the end, the grand jury brought charges against the officers who fired the most shots. Michael Oliver, who fired 31 times, and Isnora, who fired 11 bullets, will face felony manslaughter charges, according to a person who spoke with The Associated Press Saturday on the condition of anonymity because the indictment is sealed.

Marc Cooper, who fired four shots, will face a misdemeanor reckless endangerment charge, the person said. Two other officers involved in the shooting were not indicted.

The officers have said they are innocent. Prosecutors have declined to speak about the grand jury’s work and said its findings will be unsealed Monday.

The level of proof needed by a grand jury to bring a charge is low. Their burden is to determine only that it is likely than a crime was committed. But at a trial, the burden of proof is beyond a reasonable doubt.

Grand jurors declined to indict on the more serious counts of second-degree murder, and attempted murder, or the lesser charge of criminally negligent homicide.

Some legal experts say the charges were appropriate.

“The charges sound to me like some kind of compromise,” said Paul Gianelli, a prominent defense attorney and former chief assistant district attorney for Suffolk County. “From what I know, the charge seems appropriate because they caused the death of someone without making the appropriate inquiries as to criminal conduct. That was judged reckless by the grand jury.”

The officers are expected to surrender first thing Monday morning to authorities.

They will be fingerprinted and processed, and will be arraigned before a Supreme Court justice in the Queens courthouse, officials said. The defendants were rounding up bail money in anticipation of their arraignments.

Karasyk said Isnora was “very upset and disappointed, but he is looking forward to his day in court.”

Mike Carey, who fired three times, and Paul Headley, who fired once, were not indicted.

Carey’s attorney said his client was relieved.

“He testified forthrightly, he understood the questions of the jurors, he answered truthfully and to the best of his ability,” attorney Stephen Worth said.

The case has renewed allegations that the NYPD is too trigger-happy, and sparked protests by activists who say the department is too quick to judge black men harshly, a claim city officials deny.

The men who were shot were black. Cooper, 39, and Isnora, 28, are also black; Oliver, 35, is white. The other two officers – one black and one white – were not charged.

On Saturday, protesters who said the grand jury’s reported decision was not enough, marched from Union Square to police headquarters.

“These police officers, all of them involved, should be made to feel this for the rest of their lives,” said David Galarza of People’s Justice, which organized the event.

AP-ES-03-17-07 1726EDT