Police officials said that although the woman had said her son didn't have a gun, Khiel Coppin gave five officers no choice but to open fire after he suddenly charged them outside her home with a black object in his hand. It turned out to be a hairbrush.
Police Commissioner Raymond Kelly said the 18-year-old pointed the brush at officers "as if he were aiming a gun," and repeatedly ignored repeated orders to "stop, show his hands and get on the ground."
The district attorney is investigating, but Kelly said officers reasonably believed Coppin was about to use deadly force, and that their response appeared to be within NYPD guidelines.
Kelly also said Coppin had brandished a pair of knives when officers first arrived, at one point taunting police by saying, "Come get me. I have a gun. Let's do this."
Coppin's family denounced the police department for quickly concluding that the officers were justified in their response.
"Nobody but Houdini himself could have decided that in 24 hours," family attorney Paul Wooten said.
The 17-minute episode began about 7 p.m. Monday when officers arrived at the Brooklyn home in response to a report of a dispute involving a gun. The mother, Denise Owens, had summoned a psychiatric intervention team earlier in the day, claiming her son was suicidal, but he took off before the team arrived, Kelly said.
In the 911 call, while the emergency operator took down the address in Bedford-Stuyvesant, a male voice was overheard in the background, saying, "I got a gun and I'm gonna shoot you," and, "I've got a (expletive) gun!"
When a 911 operator called back about five minutes later to ask Owens for a description of her son and the weapon, she told the operator, "He does not have a firearm," a second transcript shows.
"I'm flipping out," the mother added. "I can't handle this."
When officers arrived at the home, they encountered Coppin inside with the knives. They backed off and ordered his mother and younger sister outside.
The teen began screaming from a first-floor window at his mother and officers before climbing out of the apartment window and crossing a sidewalk toward the officers while holding the hairbrush in his hand, police said.
The officers backed up and ordered him to stop, police said. When the teen refused and kept approaching them, they began shooting from a distance of 5 to 7 feet, police said. Police said eight of the 20 bullets struck Coppin, who was pronounced dead at a hospital.
"This was a terrible tragedy for Khiel's family," Kelly said.
Kelly said Coppin and had been taking antipsychotic medication had been admitted to a hospital for his mental problems.
Investigators also recovered notes they said were written by Coppin with rambling observations about death and disillusionment. One read: "Those closest 2 death iz closer 2 happiness."
The victim's brother complained his background had been distorted by the media.
"He is a human being," said Joel Coppin. "What we want is simply justice. ... We don't want headlines. We want justice for Khiel so every young black man in the city'll never go through this again."
Police said two of the shooters were Hispanic and three white.
A neighbor, Bernice Sanders, said she looked out her window Monday night after hearing the police order someone to "Get down!" She also described seeing officers with their guns drawn, taking cover behind a car.
"The boy did not respond to them," she said. "Next thing gunshots, 'Boom, boom, boom.' The young boy is laying on the ground. They handcuffed him on his back."
Patrick Lynch, president of the Patrolmen's Benevolent Association, came to the officers' defense.
"This is an unfortunate situation where the deceased convinced everyone involved -- from family members to responding officers -- that he was in possession of a gun," Lynch said. "Tragically, he sought and succeeded in forcing a deadly confrontation with police."
Police said Coppin's mother had attempted to have him hospitalized earlier on Monday, and that the teen had a history of mental illness.
The killing of an unarmed man in a hail of police gunfire brought back memories of previous high-profile incidents: the 50-bullet barrage that killed the unarmed Sean Bell on his wedding day in November 2006, and the 1999 killing of unarmed African immigrant Amadou Diallo, who was hit by 19 of the 41 shots fired by police in the Bronx.