The suicide note of Mr. Long, who was killed by the police, was included in the trove of evidence that the authorities made public at the end of their use-of-force inquiry. No officers will be charged in connection with Mr. Long’s death, a conclusion that was never in serious doubt in the Louisiana capital.
“This was a no-brainer,” Hillar C. Moore III, the East Baton Rouge Parish district attorney, said during an 83-minute presentation on Friday.
Although the police had already described many details of the attack, and although Mr. Long’s motive seemed clear, Mr. Moore’s report represented the end of the inquiry into the episode, which came 10 days after a fatal ambush of officers in Dallas.
Mr. Long’s rampage heightened fears about officer safety across the country, and by the time of his assault, Baton Rouge was steeped in turmoil after the shooting death of Alton B. Sterling, whose killing by the police led to widespread protests. (Mr. Moore said Friday that Mr. Long had used his computer to seek information, including addresses, about the two officers connected to Mr. Sterling’s death. Neither man has been charged with a crime, although a state inquiry is continuing.)
Mr. Long, a veteran of the Marine Corps, arrived July 12 in Baton Rouge, according to Mr. Moore’s report. There, he floated between hotels before driving along Airline Highway on July 17, beginning a fatal sequence of events that Mr. Moore said lasted nearly 14 minutes and included at least 149 gunshots by Mr. Long and the police.
Officers were investigating a report of a man with a rifle when Mr. Long opened fire. Wounded and clearly in distress, Officer Matthew Gerald moaned two words over his radio: “Shots fired.”
According to Mr. Moore’s report, and photographic and video evidence released Friday, Mr. Long kept firing and moving, striking more officers, before members of a special response team shot him.
Officer Gerald died in the attack, along with Deputy Brad Garafola and Corporal Montrell Jackson. Three other law enforcement officers were wounded. Mr. Long, who was shot 45 times, according to an autopsy report, died at the scene, his left hand resting atop his legally purchased semiautomatic rifle.