FRANKLIN (CBS) – The death of a Duke University student in Franklin has been ruled accidental, authorities said Friday.

Michael Doherty, 20, was found dead in the woods near Interstate 495 on May 20, six days after he was reported missing.

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Doherty left a party to walk home in heavy rain but never made it to his house. His body was found about a quarter-mile away from the party.

The swampy area where searchers looked for Michael Doherty in Franklin. (WBZ-TV)

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The state medical examiner said the cause of the death was “hypothermia brought about by prolonged exposure to atmospheric cold.”

“We find no evidence of foul play in Mr. Doherty’s death,” Norfolk District Attorney Michael Morrissey said in a statement Friday. “Our thoughts are very much with the Doherty family as they grieve Michael and live through this tragic time.”

Michael Doherty. (Photo credit: Franklin Police)

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Doherty had just come home to Franklin for the summer after completing his sophomore year at Duke.