During the first two hours of her questioning by detectives, Melissa Calusinski details the hours she spent with Benjamin Kingan on the last day of the 16-month-old boy's life.
And on the video of that questioning, shown for the first time Wednesday in a Lake County courtroom, the detectives make it clear to Calusinski they believe she is not telling them all she knows.
Calusinski, 24, of Carpentersville, is charged with first-degree murder in the boy's Jan. 14, 2009 death at the former Mini Subee in the Park center in Lincolnshire.
Her attorneys are trying to block her statements, made two days after the Deerfield boy's death, from being used against her at a trial because they claim police violated her rights.
Highland Park Police Officer Sean Curran, who is not related to Lake County Sheriff Mark Curran, and Round Lake Park Police Chief George Felinko were assigned to question Calusinski in their roles as investigators with the Lake County Major Crimes Task Force.
On the video, Calusinski walks through her day as teacher's aide at the center that closed not long after Benjamin's death and claims nothing out of the ordinary happened with Benjamin or any of the other seven children in the room to which she was assigned.
She said she and two other employees rotated in and out of the room so there was never fewer than two adults present, except for a period of "about half a minute when she was alone with the children.
Police say she eventually confessed to hurling Benjamin to the ground when she became upset with other children, causing a skull fracture a pathologist said resulted from the force equal to a fall from a two-story building.
Defense attorneys argue Benjamin threw himself backward and struck his head on the floor in a tantrum three times that day, and that activity may have contributed to his death.
Calusinski talks about the children being fed, having diapers changed, playing and taking naps before she noticed Benjamin acting unusually during the time she was alone with the children.
"I looked over and he was in his chair starting to go to sleep, Calusinski says on the video. "I went over and said 'Ben,' 'Ben,' but he didn't respond.
Other employees heard her shouting at the boy and rushed into the room, Calusinski said, and one called for an ambulance while others attempted to resuscitate him.
Benjamin was pronounced dead a short time later at Advocate Condell Medical Center in Libertyville.
Curran and Felinko respond to her version of events by telling Calusinski, who agreed to be questioned and waived her right to remain silent, that they believe she is not telling them the truth.
They tell her they believe what happened to the boy could have been accidental, but insist it could have only happened a short time before Benjamin began losing consciousness.
The detectives urge her to tell them the truth, explaining to her that if she did something or saw someone else do something to Benjamin it will be better for her to explain everything early in the process.
"There is nothing more important to us than the death of a baby, Curran tells Calusinski on the video. "I assure you we are not going away until we get to the bottom of this.
Calusinski, who begins to cry at times during the video, maintains her innocence on the portion of her interrogation shown Wednesday.
"I know for a fact that I did not do anything or see anything that could have fractured his skull, Calusinski says through sobs. "If I did see something, I would say something.
The hearing into the legality of her questioning is scheduled to resume Nov. 19.