A motive for the slayings remains unclear, but police said Julia Hudson's estranged husband, William Balfour, is a suspect. Police have been holding the 27-year-old, who is on parole and spent nearly seven years in prison for attempted murder, vehicular hijacking and possessing a stolen vehicle.
Authorities have described the incident as "domestic related."
According to their marriage license, Balfour and Julia Hudson were married Nov. 14, 2006. Neighbors and his family members said the couple had been separated for about a year.
But Balfour's mother said there was no way her son had anything to do with the crimes, adding he would never hurt his wife or stepson.
"This is not my son that did this," a distraught Michelle Davis Balfour said. "You cannot say my child did this to that girl. He loved Julia. He loved Julia's mother. My God, he put that girl's mother before me."
Michelle Davis Balfour said Donerson had ordered her son to move out of the family's home last winter, according to local reports.
According to neighbor Bernice Russell, there was "a lot of tension" between the pair, and Russell overheard another neighbor say that Balfour had threatened to kidnap Julia's son a couple weeks ago.
Russell said as far as she knew, Balfour was living with his girlfriend, with whom he was expecting a child. The Tribune reported that police had interviewed her and that her account contradicted Balfour's alibi the day of the killings.
Russell's husband, Joe, said he had been "very dismayed" by the slayings. "I've never seen this kind of violence before," he said of his neighborhood of 17 years. "They were nice people."
Now Hudson, who is experiencing great success with her recently released debut album, and her family are planning three funerals.
"We're just sad. We're going through this stage where we're just sad and in shock," Hudson's aunt, Dorothy Hudson, told The Associated Press Monday.
She and her husband, John, own a Chicago funeral home that plans to handle arrangements for the family.
The Associated Press contributed to this report.