Chicago ? Police arrested the estranged brother-in-law of Jennifer Hudson on Monday in the shooting deaths of the entertainer’s mother, brother and young nephew, taking him from a prison where he had been held on a suspected parole violation.

William Balfour, 27, was arrested at Stateville Correctional Center on a warrant accusing him of murdering the relatives of the singer and Oscar-winning actress, Chicago police spokeswoman Monique Bond said.

Until Monday, police had identified Balfour only as a “person of interest” in the investigation. He had not been formally charged as of Monday night.

Balfour’s attorney said Monday night his client told him he is innocent.