An Amber Alert has been issued for the three children and Benito Casanova, 32, who police describe as either the boyfriend or the husband of the dead woman, Sofia Garcia.
Court records show that Garcia, 30, had been granted an order of protection in February 2007 against Casanova that barred him from having contact with Garcia, her sisters or her children.
The order was valid until May 2009. But Salvador Leon, the landlord in the building where Garcia's body was found, told the Chicago Tribune in a story posted on its Web site Tuesday that Garcia and Casanova moved into the apartment in December.
In documents filed with the court, Garcia alleged Casanova had choked her and said he was "going to kill me because I did not want to be with him. He ALWAYS tells me that he is going to KILL me if I don't take him back, then kill himself."
The Amber Alert for 6-year-old Oscar Casanova, 7-year-old Karla Casanova and 11-year-old Fernando Casanova was issued Monday after Garcia's body was found. Police said Benito Casanova is the father of Fernando and Oscar.
The children were last seen Friday afternoon at their elementary school after classes let out, where police believe Casanova may have picked them up.
Casanova hasn't been charged with any wrongdoing. But police want to speak with him in regards to the children's disappearance as well as Garcia's death, which is being investigated as a homicide, said Chicago police spokeswoman JoAnn Taylor.
CBS station WBBM-TV in Chicago reports that Garcia's sister arrived at the home to pick the children up for school Monday and found her in a closet with a plastic bag over her head. An autopsy Tuesday found she died of head and brain injuries caused by multiple blunt head trauma from an assault and the death was ruled a homicide, according to the medical examiner's office.
Lorenza Valles, 40, lived upstairs from Garcia's apartment.
"She seemed like a good mom, worked hard for her kids," said Valles. Other neighbors said Garcia worked an overnight shift but was always home in time to take her children to school.
For Fernando, Karla and Oscar Casanova, Friday was apparently like any other day. The siblings went to school at Yates, then left for the day. But they haven't been seen in Chicago since.
Children, teachers and officials were distraught Tuesday at Yates Elementary as they prayed the three children would return safely.
Parents gave their children pep talks as they dropped them off for classes.
"I decided to talk to them and tell them that every parent is different - number one," said Grover Phillips, a father of students at the school. "Number two, they have parents that love them, and those kids will be found sooner or later."
"I knew the little kids; I knew the little boy; he always said, 'hi,' and 'bye;' talked," said Vanessa Aleman, a Yates mother. "They were nice kids."
"(Garcia) was seen in school Friday morning, she came for report card pickup day Thursday, and once again there was nothing out of the ordinary," said Yates Principal Harry Randell. "I want everybody to understand the children were not abducted from school."
"We don't know the person that did this to the parent or did take the children," added parent Anna Troch. "I mean, it could be anybody."
Benito Casanova was described as about 6-foot-1, 230 pounds, with brown hair and brown eyes.
Oscar Casanova, 6, is 4 feet tall and weighs 60 pounds with dark brown hair and brown eyes; Karla Casanova, 7, is 4-feet 1-inch inch tall and weighs 75 pounds with brown hair and brown eyes; and Fernando Casanova, 11, is 5 feet tall and weighs 130 pounds with brown hair and brown eyes.
Authorities said Casanova and the three children may be traveling in a 2002 silver or gray Dodge Dakota, with Illinois license plate 86196HB. One plate is missing from the car, officials said. Taylor said it's unclear in what direction they could be traveling.