William Balfour, 27, Jennifer Hudson‘s estranged brother-in-law, has been arrested and will be charged with killing her mother, Darnell Donerson, 57; Jennifer’s brother Jason Hudson, 29; and her seven-year-old nephew, Julian King. Julian’s body was found in the backseat of an SUV that had been owned by Jason and a gun was discovered in a vacant lot nearby the SUV. Balfour, who was married to Hudson’s sister Julia, had previously only been identified by police as a “person of interest.” He was formally charged Monday night. Balfour, who allegedly threatened to kill Julia’s family prior to the shootings, claims he’s innocent. He has served prison time for attempted murder and carjacking, and was on parole at the time of the shootings. Other members of his immediate family are also well-known to police — his father is currently serving a 30-year prison sentence for murder and his brother was convicted on drug dealing charges.