The gunman who set an ambush last summer for police in Baton Rouge, La., had written about killing officers and had searched for officers’ home addresses before the attack, according to a new report released Friday by the local prosecutor.

Three law enforcement officers were killed and three others were wounded on July 17, 2016, near a convenience store close to police headquarters. It happened less than two weeks after Baton Rouge had erupted in protests after the fatal police shooting of Alton Sterling. The events had Baton Rouge on edge, with emotions raw, NPR reports.

The report includes video and still images of the shooter, 29-year-old Gavin Long, an Iraqi war veteran from Missouri. He's dressed in all black with a hood and face mask, armed with a rifle over his shoulder. The video shows him shooting officers in a 13-minute ordeal that ended when Long was killed in a gunfight with a special response team.

Investigators say Long had searched online for the home addresses of Baton Rouge policemen involved in the fatal shooting of Sterling. He had posted online video calling for bloodshed in response to police-involved killings before coming to Baton Rouge on July 12.