A Wisconsin woman is accused of killing her 4-year-old son with autism, who police officials say was found burned and bound with seven belts in the bathtub of their apartment.

Amelia Di Stasio, 23, of Milwaukee, is charged with first-degree intentional murder, according to jail records. She is being held in the Milwaukee County Jail in lieu of $350,000 bond.

Fox 6 News in Milwaukee reported that firefighters were dispatched to Di Stasio's home Sept. 28 after smoke was spotted coming from the apartment. The firefighters forced their way in and found smoke coming from the stove and the bathtub.

In the tub, they found the body of Antonio Di Stasio, the news station reported. The boy’s hands were bound behind his back and there was a garbage bag secured tightly over his head.

"(A) majority of his body was burned," a criminal complaint obtained by Fox 6 News said. Antonio's autopsy revealed "significant charring" and thermal injuries.

His death was ruled a homicide, but it was not immediately clear if he died of the burns or of asphyxiation from the plastic bag on his head.

Antonio's grandfather, Ralph Di Stasio, told the news station that his daughter suffers from bipolar disorder. The grieving grandfather said he is trying to understand how she could have hurt her son.

"She loved Antonio with all of her heart," he said. "That's why this was so hard."

Di Stasio wrote on Facebook that his grandson was "bright and happy," but that his autism caused him to "act out" and scream, which caused neighbors to complain about the noise. He said the apartment where the boy died was his third home in a little over a year.

"Your (sic) all gonna be down on his mother. But she loved him," Di Stasio wrote. "Took him everywhere with her. Tried to get him treatment. And she's now under arrest. I don't know what happened, only that I've lost both my grandson and a daughter."

A neighbor of Amber Di Stasio's told police that the day before Antonio's body was found, she heard the boy crying, "Please, Mommy. Stop! I won't do it again," and then his mother yelling at him to "shut up," the criminal complaint said. The witness said she heard a banging noise coming from the Di Stasio apartment the next morning.

Antonio’s pet guinea pig was found drowned in its cage next to the bathtub, the news station reported. An open bottle of canola cooking oil was sitting on the sink and the apartment’s smoke detector had been removed and submerged in water.

Police officers who responded to the scene found Di Stasio's cellphone, on which they discovered searches asking: "How do canabals (sic) die" and "how to kill a canabal (sic)," the complaint said.

The search results included a link to the message board about an online game in which players fight cannibals, the news station reported. The messages detailed ways to kill a cannibal, with the first suggestion being to “kill it with fire.”

The board also offered details of the game, in which the cannibals "like to bathe in oil," Fox 6 News reported.

The Milwaukee Journal Sentinel reported that a witness told investigators she saw a woman who looked "frazzled" jump from the window of the apartment shortly before firefighters arrived.

Di Stasio was taken into custody a few hours later after a Milwaukee police officer spotted her walking along a street several miles north of the crime scene, the Journal Sentinel said. In her purse were identification cards for both her and her son, as well as a piece of paper with a name and phone number on it.

When an officer called the number, he talked to a man who said he’d given the phone number, which belongs to his wife, to a woman he saw crying at a bus stop that morning. The man told the officer that he’d asked the woman what was wrong.

“I did something really bad (and) I need to talk to a pastor,” the woman told him, according to the criminal complaint.

The man said he offered the woman his wife's name and number because his wife is a Christian, the Journal Sentinel reported. Investigators showed the man a photo array, from which he identified a photo of Di Stasio as the woman he'd met.

Antonio's family members told Fox 6 News that they are struggling to understand his death.

“He was a good kid. Always smiling,” his uncle, Juan Allen, said. “It’s just sad. That’s an innocent life that’s gone. I’m just trying to cope with the pain right now.”

The boy's aunt and Amelia Di Stasio's sister, Eva Allen, told WTMJ-TV that she is angry with her sister.

“I love my sister regardless, you know, and I know she was sick. I want to tell her I’m angry. I’m very upset with her,” she said. “I just want to know why.”