Police arrested the estranged brother-in-law of Jennifer Hudson in connection with 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 Centre on a warrant accusing him of murdering the relatives of the singer and Oscar-winning actress, said Chicago police spokeswoman Monique Bond.
Until now, police had identified Balfour only as a "person of interest" in the investigation. He had not been formally charged as of on Monday night, said Tandra Simonton, spokeswoman for the Cook County state's attorney's office.
Balfour's attorney said that his client told him he is innocent.
"He vehemently denies that he is guilty in this case," Joshua Kutnick told reporters outside police headquarters.
"Any evidence pointing to Mr Balfour is not even thin. It is very, very weak," Mr Kutnick said.
The bodies of Jennifer Hudson's mother, Darnell Hudson Donerson, and brother, Jason Hudson, were discovered October 24 at the family's home on the South Side of Chicago. The body of seven-year-old Julian King was found three days later in a sport utility vehicle on the West Side. All three had been shot.
Police took Balfour into custody the same day the bodies of Donerson and Hudson were discovered. After 48 hours -- the longest Chicago police can hold a person without charges -- Balfour was taken by the Illinois Department of Corrections on the suspected parole violation.
Balfour -- Julian's stepfather and the estranged husband of Jennifer Hudson's older sister, Julia Hudson -- served seven years for a 1999 attempted murder and vehicular hijacking conviction.
Balfour had refused to take a lie-detector test and stopped cooperating with detectives, according to a police official