(CNN) -- Chicago, Illinois, police arrested a man Monday in connection with the killing of three relatives of singer-actress Jennifer Hudson, a police spokesman said.
William Balfour, here in an undated photo, is the estranged husband of Jennifer Hudson's sister, Julia.
William Balfour, 27, was first detained for questioning on October 24, the day Hudson's mother and brother were found shot to death. Authorities said at the time that they were holding Balfour for an unspecified parole violation.
Hudson's mother, Darnell Donerson, and brother, Jason Hudson, were found shot to death in their South Side Chicago home. The body of her nephew, 7-year-old Julian King, was found three days later in an abandoned SUV on Chicago's West Side.
Police later found a handgun near the vehicle.
Detectives served arrest warrants on Balfour on Monday afternoon, said Chicago police spokeswoman Monique Bond.
Balfour was transferred from the Statesville Correctional Center to the custody of detectives in the case, she said, and he is awaiting formal charges on three counts of murder.
Balfour is the estranged husband of the singer's sister, Julia Hudson, and the stepfather of Julian King.
According to the Illinois Department of Corrections, Balfour spent nearly seven years in prison for attempted murder, vehicular hijacking and possessing a stolen vehicle. He was free on parole at the time of the shootings.
Hudson won a best supporting actress Oscar for her portrayal of Effie in the film version of the Broadway musical "Dreamgirls." She competed on the third season of the singing competition "American Idol" in 2004, becoming one of the top seven contestants before being eliminated from the contest.
Michele Davis-Balfour, Balfour's mother, passionately defended her son Monday to reporters. She said that at least one of the witnesses that police used to build a case against Balfour was lying.
"My son did not do this. I am sick of this. They need to focus on somebody else," Davis-Balfour said.
She said Balfour has an alibi: He was with one of his three girlfriends the night of the slaying.
"He was with Diana that night and with Kate in the morning," she said.
Balfour's attorney Josh Kutnick also said Balfour has told him that he did not commit the crimes.
"He believes when the evidence comes out, he will be found not guilty," Kutnick said.
CNN's Susan Roesgen contributed to this report.
All About Jennifer Hudson • Chicago
Chicago, Illinois police arrested William Balfour, the estranged brother-in-law of Oscar-winning American actress and singer Jennifer Hudson, on Monday, multiple media outlets reported. Balfour is expected to be charged with three counts of murder for the slayings of three of Hudson's relatives in October.

Hudson holds her Oscar. "We have obtained an arrest warrant for William Balfour. He was released to Chicago detectives," Chicago Police Department spokeswoman Monique Bond told Reuters.

Hudson's mother, Darnell Donerson, 57, and brother, Jason Hudson, 29 were found dead in Donerson's home on October 24 and the body of Hudson's 7-year-old nephew, Julian King was found four days later in a stolen SUV. A handgun police say is tied to the case was found nearby, but Reuters reports that Bond did not comment on any evidence in the case.

The Associated Press reports that police took Balfour into custody on Oct. 24 and held him for 48 before the Illinois Department of Corrections took possession of him on an alleged parole violation. Balfour previously served nearly seven years for a 1999 conviction attempted murder, vehicular hijacking, and possessing a stolen vehicle. CNN reports he was out of jail on parole at the time of the shootings.

Balfour's mother, Michelle Davis-Balfour, spoke to the press Monday night, saying she thought that there was no case against her son.

"If they found gun powder on his hands, you got a case; if they found a gun on him, he had a case; if they found a fingerprint on the truck that he did this, you got a case; but they don't have nothing," Davis-Balfour said, according to the Associated Press. She also said: "My son did not do this. I am sick of this. They need to focus on somebody else."

Davis-Balfour also accused at least one witness of lying while providing an alibi for his son, saying he was with one of three girls friends when the killings happened.

"He was with Diana that night and with Kate in the morning," she said, according to CNN.

Attorney for Balfour, Josh Kutnick, told CNN that his client is innocent. "He believes when the evidence comes out, he will be found not guilty," Kutnick told CNN.

Hudson became famous in 2004 when she was one of the finalists on the third season of the American hit television show ''American Idol''. She later won multiple awards for her role in the 2006 motion picture ''Dreamgirls''.