As new details emerge it's been discovered that Ismaaiyl Brinsley, the gunman who killed two police officers in New York on Saturday, had posted specific threats against the NYPD for weeks before the attack.

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Robert Boyce, NYPD's Chief of Detectives, told BBC News on Monday that Brinsley had been using social media to threaten law enforcement following the verdicts surrounding the deaths of Michael Brown and Eric Garner.

Boyce noted that the 28-year-old Maryland native had shared sentiments of "self-despair and anger at himself and where his life was" leading up to the shooting.

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Brinsley shot and injured his ex girlfriend, 29-year-old Shaneka Thompson, in Baltimore, Md. before heading to New York on Saturday.

After arriving in the city, Brinsley picked out a police patrol car and fired a semi-automatic handgun at the vehicle, killing officers Wenjian Luis, 32, and Rafael Ramos, 40.

According to Boyce, Brinsley spoke with two men on the street before murdering the officers. "He asked them for their gang affiliation," noted the Chief of Detectives. "He asked them to follow him on Instagram, and then he says: 'Watch what I'm going to do.'"

Following the shooting Brinsley ran to a subway station nearby where he shot and killed himself with a bullet to the head.

On Sunday CBS News announced that law enforcement in cities across the nation will remain on "high alert" for fear that others will try to imitate Brinsley's actions in New York.

Tags: police shooting nypd