Police on Monday were looking into why a stun gun apparently failed after a knife-wielding man lunged at officers and then was shot to death.
Emmanuel Paulino was shot several times by officers on Sunday morning after he refused to drop a 6-inch knife, police said. A sergeant fired a Taser stun gun at Paulino, hitting him with two wired prongs meant to stick into his body and shock him, but it was unclear if both prongs stuck, they said.
Paulino pulled one of the prongs out of his body and kept advancing, police Commissioner Raymond Kelly said.
Officers retreating from Paulino were backed into parked cars and yelled for him to drop the knife before they fired their handguns, police said. Paulino was hit by bullets several times and died.
It was unclear why the stun gun didn't work. When the device is ineffective it's usually because only one of the probes hits a suspect or clothing is too heavy for the shock.
A spokesman for Taser, Steve Tuttle, said the company's stun gun is 94 percent effective in the field.
"It's not a magic bullet," he said.
Thousands of police sergeants began carrying Tasers on their belts in 2008 after the New York Police Department expanded use of the weapons, a trend that has been playing out in police departments across the country in recent years.
The pistol-shaped weapons fire barbs up to 35 feet and deliver powerful shocks to immobilize people. Each barb looks like a bullet with a needle on one end. Some organizations are strongly opposed to the stun guns' use in police departments, fearful that they can be abused without clear guidelines.
But the weapons, if used effectively, can safely subdue an out-of-control suspect before he or she harms anyone, including the responding officers.
Former NBA star Jayson Williams was zapped with a stun gun by police in his swank hotel suite in April 2009 after he resisted attempts by officers, who had been told he was suicidal, to take him to a hospital. He was not seriously injured.
Last year, the police department's Medal of Honor winner, Sgt. Timothy Smith, was stabbed in an eye with a kitchen knife by a man on whom a stun gun had no effect. Officers were able to subdue the man.
But in 2008, an emotionally disturbed Brooklyn man plummeted headfirst to his death from a building ledge when police stunned him with a Taser. The police commander who ordered an officer to fire the stun gun later committed suicide after apologizing to the man's family. After the man's death, Kelly ordered refresher training on how the department handles mentally ill suspects.
The officers involved in Sunday's shooting, in the Inwood section of upper Manhattan, appeared to follow protocol, Kelly said Monday. They had requested help from the department's elite Emergency Services Unit, which deals with emotionally disturbed people and was en route when the shooting occurred.
Police released an audio transcript of a 911 call they say Paulino made before the shooting. When the 911 operator answered, a man said, "Yeah, I want you to call the cops 'cause I'm ready to kill."
"OK, so what's going on there?" the operator said.
"Yeah, I'm ready to kill cops right now," the man said.
Kelly said Paulino had apparently gotten into a fight with his girlfriend earlier. The shooting incensed some neighborhood residents, who described Paulino as having emotional problems.
Nine witnesses told investigators that before police fired they saw a man armed with a knife continue to charge at police officers despite repeated commands to stop and drop the weapon, police said.