Prosecutors release surveillance video of KC man’s ambush of police last year in Baton Rouge

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BATON ROUGE, La. --  A necessary evil. Those are the words from a Kansas City man authorities say was behind a police ambush last year.

Investigators said ex-Marine Gavin Long traveled to Baton Rouge with a deadly plan. He killed 3 police officers before responding officers killed him.

Prosecutors are now releasing video of the shooting, and a suicide note found in Long's car.

In the note, Long said he hopes the good cops -- which he felt are the majority -- would stand together and enact justice against bad cops.

A childhood friend of Long told FOX 4 last year that the man he remembers a totally different person than the violent, troubled young man Long became.

"I don't know him as that person, I just know him as my next door neighbor that was kind of like my brother at the time," Jacob Bellew told FOX 4. "He was one of those people that I never knew what happened to him."

Bellew said he and his family used to go next door and eat dinner with Long and his family.

"He was intellectual, he was smart, he had a lot of wisdom," he said. "It still doesn't seem real, you know, that he would go out like that when he had so much more to offer to the world."

The District Attorney's Office report concluded the officers were justified in killing Long.