The suspect — pictured above — entered the building on North 13th Street, went to the eighth floor, and walked into the unlocked office, where he sexually assaulted the unnamed victim around 2:15 p.m., Philadelphia police said.
The man was last seen walking south on 13th Street, police said.
He was wearing a black baseball cap, a black T-shirt, blue jeans with a black and silver belt, and a gold watch on his left wrist, according to police.
Anyone with information on his whereabouts is urged to call 911.
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