CONCORD, N.H. — The stepfather of a man charged with killing his 70-year-old mother while she was in a New Hampshire hospital says the man had a long history of erratic and violent behavior he blamed on post-traumatic stress disorder from his time in the military.

Bob Ferriere tells The Associated Press that Travis Frink struggled for the past decade with PTSD after he returned from the military with a traumatic brain injury. He says when Frink was not on his medication he would go “wacko,” beating people up and threatening others with a gun. He says Frink lost three or four jobs.

Frink, of Warwick, Rhode Island, is accused of fatally shooting Pamela Ferriere on Tuesday at Dartmouth-Hitchcock Medical Center in Lebanon, where she was being treated for an aneurysm.

Frink has pleaded not guilty to murder.

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Travis Frink, of Warwick, Rhode Island, stands with his attorney, Public Defender Rebecca McKinnon, during his arraignment in Grafton County Superior Court in North Haverhill, N.H., on Sept. 13, 2017. Frink, 48, is charged with first-degree murder in the death of his 70-year-old mother, Pamela Ferriere, on Tuesday in the intensive care unit at Dartmouth-Hitchcock Medical Center in Lebanon, N.H. (Jennifer Hauck/The Valley News via AP, Pool) (Associated Press)