BATON ROUGE - The mother of the Iraq war veteran who shot and killed three law enforcement officers in Baton Rouge says she believes her son suffered from post-traumatic stress disorder and that he once said he thought the CIA was following him.

Gavin Long's mother, Corine Woodley, told PBS talk show host Tavis Smiley on Thursday that her son would "pretty much lose it" and become furious every time he heard about a black man being shot by police in what he considered an unlawful manner.

She says he would tell her, "Somebody has to do something."

Smiley taped his interview of Woodley in Los Angeles. Woodley brought a letter to the studio from the Department of Veterans Affairs denying her son's request for treatment of PTSD in 2013 on grounds that the disorder wasn't related to his military service.

Police gunned down Long, a 29-year-old former Marine from Kansas City, Missouri, after he shot and killed three officers and wounded three others during a shootout Sunday.