New York police are trying to determine what prompted a teenager to trick police into thinking he was an armed carjacker, chase him to a dead-end street, and then apparently goad them into killing him by pointing a pellet gun at the officers.
"Everything that we know, we would be able to use that term suicide-by-cop," Lt. Troy D. Little, with the New York State Police, told ABC News.
"We're trying to identify anybody who might give us some insight to Justin, family siblings, other relatives, other friends, co-workers, just anybody that might have been in touch with him in recent times," said Little.
Early Thursday afternoon, 911 received a call reporting an armed car robbery. Dispatchers relayed a description from the caller telling police the suspect was a young, white male wearing sunglasses and driving a silver car. The description matched Arnold.
Police spotted the car in Canastota Village, about 25 miles from Syracuse. They tried to stop the driver, but he fled, leading two police officers and a state police sergeant on a four mile chase that led to a dead-end road in Madison County.
When the 17-year-old got out of the car, police told him to show his hands. Instead, he pointed the black pellet gun at the officers.
The police officers fired 10 rounds at Arnold, four of which hit and killed the teen.
It was later determined that it was Arnold who made the 911 phone call reporting an armed carjacking.
"Those things definitely suggest that he wanted to die, there's no doubt about it," said David Klinger, a criminology professor with the University of Missouri and author of "Into the Kill Zone," for which he interviewed several officers involved in suicide-by-cop shootings.
"All indications thus far reveal that these officers made a split-second decision and performed their jobs properly, faced with what they believed to be a hand gun pointed at them," said State police Capt. Mark Lincoln, at a press conference Thursday night.
Klinger said there can be an emotional toll on officers involved in suicide-by-cop deaths.
"So many officers get upset at the fact that they took a life in a script that is not part of the police program," said the criminology professor. "The police program is to use deadly force to protect themselves from criminals, bad guys, not to play out somebody's suicidal fantasy."
New York state police offered the officers involved in the shooting counseling services.
"I know they'll be availing themselves of that," said Little.