Authorities say 4-year-old Tate Thurman of East Peoria died from multiple blunt force trauma inflicted by his father's girlfriend.
Lesli Jett, 33, now faces first-degree murder charges in Tazewell County. Peoria County Coroner Jamie Harwood said her initial story clearly didn't add up.
"I went up to the hospital the night he was pronounced brain dead, and did an initial examination on Tate, and shot well over 100 photographs looking at the injuries. And I knew what was reported to us was not consistent to that. But what was consistent was abuse," Harwood said.
Thurman was rushed to OSF Saint Francis Medical Center on Feb. 18 from his family's 109 Jefferson Court home, and declared brain dead on the 20th. He was taken off life support following organ donation.
"Make no mistake about it. This is an abuse case. This is a case where it was immediately apparent to fire and rescue that this case was not as Ms. Jett described it as a slip and fall," said Tazewell County State's Attorney Stewart Umholtz at a Thursday news conference.
Police detectives and the Illinois Department of Children and Family Services (DCFS) were notified. Two other children living in the East Peoria home were removed for their safety.
Jett was arrested Wednesday during a traffic stop at a Creve Coeur gas station without incident. She's currently being held without bond at the Tazewell County Jail.
It's a case that's hit many hard in East Peoria - particularly in the first responder community. Police Chief Steve Roegge said the city doesn't see many murders, and even fewer of those involve children.
"Is this a struggle? Absolutely. There's a difference of each case and how it affects them," he said. "So we will make sure to take care of our officers."
Police detectives have conducted 110 hours of investigation and 12 interviews over the past eight days.
Thurman's funeral is set for Thursday.
"Our thoughts should be with the family, our thoughts should be with regard to Tate, and with our community. Because our community is a victim whenever a child is murdered," Umholtz said.
Umholtz said this is the type of case that keeps him up at night.
The state's attorney also said his office holds information close to the chest to protect the integrity of the case. He decried one person who leaked confidential juvenile records on social media linked to the Thurman case.
"You can be really brave sitting behind a telephone, or a keyboard, or releasing information on social media," he said. "But it doesn't mean it's not harmful, it doesn't mean it's not illegal, and it doesn't mean there will not be consequences for releasing this information."
He said more information will be released in a prosecutor's affidavit when formal charges are filed.
East Peoria Mayor John Kahl said he thinks much of what's currently circulating around social media about the case is doing more harm than good.
"This is truly a tragic case. In the pursuit of justice, there's many things that go into that. And I just ask people to keep things respectful...keep the friends and family of Tate in your prayers," said Kahl. "Lift them up if you can. There's many people, not just family and friends suffering, but others, as well. But there's still a job to do for many people."
Authorities haven't announced any additional arrests in the case. The investigation is described as ongoing.