A woman in Upper Tyrone Township came home to hear her sister screaming from her room on Tuesday.
When woman went into the room, she saw her 22-year-old sister with special needs handcuffed to a bed with a swollen face from a chain wrapped around her neck and a bicycle chain around her waist.
Authorities said she took cell phone pictures and videos and freed her adopted sister before calling the police.
According to the criminal complaint, shortly after the young woman called the police, her 55-year-old mother, MaryLou Dewitt, came home.
She then allegedly grabbed any evidence and fled.
Using cell phone data, the police found the mother driving on the Fort Pitt Bridge in Pittsburgh and arrested her.
Dewitt faces numerous charges, including false imprisonment, unlawful restraint and neglect of care.
No word on the current condition of the victim.