The murder occurred in a home in Naperville, prosecutors said Thursday morning at a bond hearing.
Elzbieta Plackowska, 40, was charged with two counts of first-degree murder in the stabbing death of her son, Justin, and Olivia Dworakowski on Tuesday night at a home in suburban Chicago. She was denied bail this morning during her first court appearance.
Plackowska told investigators several stories, initially blamed the attack on a stalker who got into her house in Naperville, 25 miles west of Chicago. She later said the children had evil within them and she was fighting against the devil in the house, DuPage County State's AttorneyRobert Berlin said at a bond hearing.
Plackowska finally admitted that she was angry with her husband, who works as a truck driver and is gone often, because he left her alone to care for his son, Justin, and works as a maid, which she felt is beneath her dignity, Berlin said.
"She told detectives that she thought that killing Justin would hurt her husband as she hurt in their relationship," Berlin said.
Berlin said Plackowska told investigators she found the children jumping on the bed and then attacked them, also cutting their throats.
"She took a knife and ordered both victims on their knees and started praying. She began to stab her son Justin and said he was going to heaven tonight. He begged for his life and told her to stop. She continued stabbing him until he was dead," he said.
"She then turned her attention to the 5-year-old Olivia and began to stab her with a knife several times."
Berlin said Plackowska killed the girl, Olivia Dworakowski, because the child had witnessed the attack on her son.