(CNN) -- His room smelled of urine and feces. It had no lighting, no bathroom, and there was only a mattress to furnish it.
That's what police in South Florida found when they responded to an anonymous tip on Thursday evening of a woman keeping her 30-year-old autistic son in "dungeon-like conditions."
"Police found the man's room to be a small room with a blacked-out window and a rusted iron door with a lock accessible only by the outside," said Michelle Hammontree-Garcia of the Sweetwater Police Department, west of Miami.
The woman was arrested on charges of with aggravated abuse and neglect of a mentally disabled adult and false imprisonment, according to the police report.
Police said the man had scratches all over his body and is under medical evaluation at a local hospital.
Neighbors told CNN affiliate WSVN that the woman would leave her son in their mobile home by himself.
"No, she doesn't take care of him; she goes to play bingo, and she leaves the son alone," said neighbor Raphael Cruz.
Police said it wasn't certain if the man was being held against his will or if other people were staying there. Officers have been called to the residence before.
"That is being determined right now," said Hammontree-Garcia. "What was told to us by the anonymous caller is that he was held for hours at a time inside the room, while the mother left, but that was reportedly."
CNN's Kim Segal, Elwin Lopez, Dave Alsup, Tina Burnside and Rich Phillips