A New York City police lieutenant committed suicide on Thursday, eight days after ordering the use of a Taser stun gun against an emotionally disturbed man who then fell to his death, police said.

Lt. Michael Pigott had been on desk duty since the Sept. 24 incident, when police responded to an emergency call saying that a man, Iman Morales, 35, was behaving erratically in his Brooklyn apartment.

Police chased Morales naked through the building and then he stepped onto a ledge. After a standoff, Pigott, a 21-year veteran of the police department, ordered a sergeant to fire a Taser at Morales.

Morales fell 10 feet (three metres) to the sidewalk and died of severe head trauma.

Police Commissioner Raymond Kelly later said the use of the Taser violated department rules and ordered additional training.

Pigott went to Brooklyn's Floyd Bennett Field early on Thursday morning and took a gun from a police locker room. He was discovered dead with a bullet wound to the head, spokeswoman Det. Mindy Diaz said.

Stun guns have been used by New York City police since 1984, and a police-commissioned study released earlier this year said police should make broader use of the stun guns.

The report was commissioned following the 2006 shooting death of Sean Bell, who was killed by police in a barrage of 50 shots on the day he was to be married.

In a similar case nearly a decade ago, four police officers who fired 41 shots were acquitted in the death of an unarmed West African man, Amadou Diallo.

Critics say that while the use of Tasers might reduce the number of deadly police shootings they worry about overuse.