A University of South Alabama police officer was cleared of wrongdoing on Friday by a grand jury who said he was defending himself when he shot and killed 18-year-old freshman Gil Collar, AL.com reports.

In a press conference Friday, Mobile County District Attorney Ashley Rich told reporters that Collar was high on a relatively new hallucinogenic drug called 25I-NBOMe.

The drug helps to explain the bizarre sequence of events that led to Collar's death on Oct. 6 and the national controversy that followed. The Associated Press reported that Collar was running through campus nude, apparently under the influence of what was originally thought to be LSD. Collar allegedly banged on the campus police station's windows, prompting Officer Trevis Austin to exit the station -- gun drawn -- to investigate.

Police said Collar repeatedly charged Austin. The student's mother, Bonnie Smith Collar, disputed the police chief's recollection, saying surveillance tape showed that the slightly built, unarmed, and naked young man never came within five feet of the officer and didn't pose a threat extreme enough to justify shooting him from less than 10 feet away.

Public opinion divided between those who argue the officer responded to a real threat to his safety posed by a then-irrational individual and others who contend the officer overreacted to a simple security problem with a gun, rather than nonlethal means like pepper spray, a stun gun or a baton. While students carried signs that read, "Gil was murdered," CNN's Piers Morgan noted that sometimes young people experiment with drugs and learn from it, and sometimes the experimentation goes horribly wrong.

"Gil Collar could have been my son," Morgan said.



But the district attorney told reporters, "We explored every single aspect of this investigation" before determining that the officer was, in fact, in danger and acted to prevent losing his firearm.

As for Collar's normally peaceful character, Rich said, "More than likely, after the powerful hallucinogenic effects of the drug had worn off, he would have gone back to being that very same person that was described by so many community leaders."

A lawsuit brought against the university by the Collar family was dismissed in early February, but lawsuits against Austin and the university's police chief continue.

CLARIFICATION: A line referencing the legality of the drug 25l-NBOMe was removed. Several months after this story, in November 2013, the U.S. Department of Justice placed the drug in a temporary illegal status.