The man accused of opening fire in Olde Town Arvada in Arvada, CO, and killing a police officer had written about his anti-law enforcement beliefs before the attack.

KDVR reports that the police found a 4-page document believed to have been written by the shooter--identifed by police as Ronald Troyke, 59--before his death and found at his apartment.

During a news conference Tuesday, Arvada Police Chief Link Strate said the gunman targeted Officer Gordon Beesley.

John Hurley was also killed during the attack in Olde Town. He was not a law enforcement officer but according to Chief Strate he “likely disrupted what could have been a large loss of life.”