The Special Investigations Unit is probing the death of a 24 year old woman at the Niagara Falls police station.
The SIU says police arrested the woman around 5:00 Wednesday afternoon for breaching conditions.
She was taken to the station and placed in a holding cell.
The SIU says the woman left her cell around 2:00 yesterday afternoon for a bail hearing by phone and then was returned.
A few hours later, officers found the woman unresponsive and she was pronounced dead after EMS arrived on scene.