BALSAM LAKE, Wis. (WCCO) — The Polk County Sheriff’s Office says an autopsy to determine the cause of death for a 2-year-old boy found in a trunk has been completed.

The Polk County Sheriff’s Office released preliminary autopsy results Friday afternoon, which indicate that Isaiah Theis died of hyperthermia. The report said he was a normally developed, well-nourished 2-year-old. There were no life-threatening traumatic injuries or natural disease processes identified, and a full body radio graph didn’t identify any fractures.

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“There are a lot of people who cared for little Isaiah and we did what we could to find him,” Tammy Winchell said.

The sheriff said the investigation is currently working to determine whether the boy’s death was an accident, but they are still not ruling anything out, including the possibility of foul play, though there is no direct evidence to suggest that, Sheriff Pete Johnson said.

“It’s hard to see a young one gone already,” Jeni Winchell said.

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Theis, who went missing in western Wisconsin for more than 24 hours, was found inside the trunk of a car Wednesday, much to the disappointment of volunteer searchers who say police told them the cars in the area were cleared.

Johnson said that a law enforcement officer found Theis deceased just after 10 p.m. The boy was found inside a Chevrolet Impala near his home in Centuria.

The sheriff’s office said Thursday that the Impala had been looked into several times, and searchers were told that the car was locked prior to the boy being reported missing.

The Impala belonged to someone who had dropped it off at a repair shop near the property. It was when the Impala’s owner went to move it Wednesday that an officer checked and found Isaiah’s body inside.

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“Obviously this is the worst ending we could have come to,” Sheriff Pete Johnson.

John Lauritsen