Matusz Plackowski said his mother, Elzbieta Plackowska, was deeply saddened by her father's recent death but was otherwise "acting normal" until just days before she fatally stabbed his younger brother and another child she was baby-sitting and two dogs.
Plackowski, 23, testified on the second day of his mother's murder trial. Plackowska faces 12 counts of first-degree murder and two counts of aggravated animal cruelty stemming from the October 2012 attack. Her attorneys say she was insane at the time of the killings.
He said his mother's mood changed drastically the night of Oct. 27, 2012, after a social media post alerted the family to her father's death in Poland. She became irrational and more argumentative than usual.
"The next morning she went to church and said a weight had been lifted off her from church," Plackowski testified. "She said we should all go to church more often because she saw a little of the devil in all of us."
It wasn't this first time she had referenced "seeing the devil" in him and other family members, but he said he never thought anything of it.
"I took it to mean we all have our flaws," he said.
He said she kicked him out of the house after an argument the following night.
The next night, Elzbieta Plackowska stabbed her 7-year-old son, Justin, more than 173 times and 5-year-old Olivia Dworakowski 90 times at the Naperville condo where Olivia lived with her mother and dog, Nicky, on the 800 block of Quinn Court.
Plackowski said that shortly after the murders, around 11:15 p.m. Oct. 30, his mother arrived at the house of the family friend where he had been staying.
"She looked like she was in a panic and she was covered in blood," he testified. "Her face, arms, chest and shirt (were covered)."
Plackowski said his mother told him "a few different stories" about what happened.
"She said she was attacked by a man wearing all black and he looked like the devil," he said. "She said she was trying to protect the children but she got away as he was trying to stab her."
He said he was confused by her story because she would alternate saying the children were alive at the house and that the children were dead.
"It was a strange story," he said. "If someone was attacking my brother, I would stay there and help him. I wouldn't run away."
Several Naperville police officers testified to responding to the 911 calls that alerted them to the murder. They said they initially believed they were responding to an armed robbery down the street from the Dworakowski residence. As more information came in from other 911 calls and investigating officers, they zeroed in on the condo on Quinn Court and ultimately decided to kick in the locked front door to find the children.
Plackowska covered her face with her hands as photos of the dead children were shown on a screen and Naperville officer Vincent Clark described the horrifying scene.
"We stopped and slowly took this all in," Clark said of finding Olivia in her mother's bed. "We don't see this every day."
Prosecutors say Plackowska committed the murders because she was angry with her husband and felt she "got a raw deal in life."
However, her attorneys say she suffers from mania, the most severe level of bipolar disease, and should be found not guilty by reason of insanity.
If Plackowska is found to be not guilty by reason of insanity, she could be confined to a state mental hospital rather than prison. If found guilty and sane, she could be sentenced to natural life in prison.
Testimony resumes at 10 a.m. Thursday.