The call came just after 3:30 p.m. on Oct. 30: a 6-month-old boy was hurt, bleeding from his face, and he needed help.
Within days, Wisconsin investigators say, they would learn the truth: The baby was the victim of a series of panicked blows that fractured his skull, again and again. His suspected killer? A 10-year-old.
While investigators have provided few details about the killing — withholding the names of both the infant and the preteen suspect — an arrest report obtained by PEOPLE describes both the short timeline leading up to the homicide, inside a home-based day care center in Tilden, and what happened after.
The arrest report indicates that an initial 911 call about the injured baby was received at 3:40 p.m.
That call was made by Amber Sweeney, who operates the day care center out of her home. (The business has since voluntarily suspended operations pending the homicide investigation.)
The police report also indicates that the 10-year-old girl was living with Sweeney, who is a foster mother. Authorities say the girl was removed from her biological parents’ home in September and placed into foster care, though it is unclear why.
On Oct. 30, Sweeney told police that six children had been left in her care that day, including the 10-year-old girl and the infant who died.
“Sweeney stated she had put the infant down for a nap around 3 p.m.,” the report reads, noting the 10-year-old “arrived by school bus at around 3:40 p.m,” not long before the 911 call about the bleeding baby.
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According to the report, Sweeney and the kids — “except [for] the infant who was still sleeping” — went outside after the girl got back from school.
“Sweeney stated that children were in and out of the house for short periods of time,” the report explains. “Sweeney stated she instructed the children to stay out of the house due to the infant sleeping.”
However, Sweeney told police she noticed the girl “in the house sitting on the kitchen bay window” and she “was in the house by herself at that time.”
(Reached by PEOPLE, Sweeney’s husband said they could not comment due to the ongoing investigation.)
During the course of their investigation, detectives recovered a dozen items from the Tilden home they believe could have been used to hurt the baby, the report shows.
Medical personnel told authorities the boy’s injuries were consistent with “a heavy force” or pressure — “child abuse, not by accidental circumstances.”
On Thursday, the same day the boy died after being hospitalized, the 10-year-old provided police with information that “was not consistent from what investigators had discovered at this point in the investigation,” the report alleges.
Then, on Friday, the girl was interviewed again by police and “initially denied any [intentional] acts in harming the infant, but later confessed to her involvement,” according to the report.
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The 10-year-old, who is being held in lieu of $50,000 cash bail, appeared in court on Monday where she sobbed into her mother’s arms.
During the hearing, Chippewa County District Attorney Wade Newell told the court the girl told police she accidentally dropped the baby, leading him to hit his head on a stool. The baby boy then started crying.
“She panicked and didn’t know what to do and didn’t want to get into trouble,” Newell said, “and then she proceeded to stomp on the 6-month-old’s head.”
The girl’s attorney, Kirby Harless, could not immediately be reached for comment by PEOPLE. The girl has not yet entered a plea.
She has been charged as an adult. Her case is likely to move to juvenile court but, because she is at least 10, the charge was required to begin in adult court, according to the Minneapolis Star Tribune.