Lupita Nyong'o Stolen Dress -- Thief Gets Away with It ... Case Closed

The guy who burglarized Lupita Nyong'o's hotel room and stole what he THOUGHT was a $150,000 dress has gotten away with the crime, because Calvin Klein wants the whole thing to go away.

Law enforcement sources tell TMZ ... reps from Calvin Klein contacted the L.A. County Sheriff's Dept. earlier this week and said they had no interest in pursuing the case now that they got the dress back ...and it's pretty obvious why.

The thief called TMZ Friday and indignantly said he took 2 of the pearls down to the L.A. Garment District for appraisal, only to learn they were fake and worthless. He told us he had returned the dress to The London West Hollywood hotel and left it under a sink in a 2nd floor bathroom. We told the cops, and they got the dress.

We're told the Calvin Klein people did not tell cops why they did not want to pursue the case, but it's pretty obvious. The dress was represented as the real deal, and the dressmaker clearly doesn't want to put a spotlight on the phony pearls.