A special prosecutor says Albuquerque police unnecessarily escalated an encounter last year that ended in the fatal shooting of a homeless man.

Special Prosecutor Randi McGinn said Monday that 19 officers with more than 700 rounds surrounded James Boyd for camping illegally and allowed two officers to shoot him.

McGinn made her opening statements during a preliminary hearing for Officer Dominique Perez and former Detective Keith Sandy, who are facing murder charges. A judge will decide if they go to trial.

Boyd, who was mentally ill, was shot during a March 2014 standoff. Video showed Boyd appearing to surrender before Perez and Sandy opened fire. Authorities have said he threatened officers with two knives.

Defense attorneys say their clients did nothing wrong.

Boyd's death came amid a wave of police shootings in Albuquerque.