Oregon ? Former Vice President Al Gore was cleared Friday of allegations he groped and assaulted a masseuse in a luxury Portland hotel room in 2006, closing a case that could have tarnished the Nobel prize winner’s reputation.

After a four-week investigation that included interviews with Gore, masseuse Molly Hagerty, her acquaintances and hotel staff, as well as testing a pair of stained pants belonging to Hagerty, Multnomah County District Attorney Michael Schrunk said Friday there was no basis for prosecution.

In a memo to Schrunk released with the decision, Senior Deputy District Attorney Don Rees cited “contradictory evidence, conflicting witness statements, credibility issues, lack of forensic evidence and denials by Mr. Gore.”