Jennifer Hudson’s 7-year-old nephew, Julian King, is still missing after the Oscar-winner’s mother and brother were found murdered Friday at Hudson’s childhood home in Chicago.

An Amber Alert has been issued for the boy and the FBI has also joined the search. William Balfour, the estranged husband of Hudson’s sister Julia, is in custody. His mother, Michele Davis Balfour, claims he had nothing to do with the double homicide.

Hudson returned home to Chicago on Friday from Tampa, Florida. Her personal publicist, Lisa Kasteler, released the following statement to PEOPLE:

“We can confirm that there is an ongoing investigation concerning the deaths of Jennifer Hudson’s mother, Darnell Donerson, and her brother, Jason Hudson. No further comment will be made and the family has asked that their privacy be respected at this difficult time.”