The stepsister of the man who 'nonchalantly' shot and killed three people at a Thornton Walmart last week says his personality changed after a bad LSD trip years ago.

47-year-old Scott Ostrem is charged with multiple counts of first-degree murder and attempted murder, but his family says drugs made him a different man.

According to Fox News, his stepsister told The Denver Post that Ostrem was tormented by voices, and claimed that 'the devil was after him,' ever since he took LSD at a party in the '80s.

Associated Press reported that 'he had been outgoing, sociable and athletic before taking LSD at a party in 1988, and afterward he became a recluse haunted by voices saying the devil was after him,' and even had a priest perform exorcisms.

LSD is obviously dangerous, and it can have some really bad neurological side effects, but if you're thinking a hallucinogenic drug trip from three decades ago may not the right thing to blame for a shooting, then you're not alone.

AP also spoke with a psychiatry professor at UCLA, Charles Grob, who said that LSD taken in 1988 is likely not the cause of his actions.

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