An autopsy confirms the death of a young boy found inside a car last month was accidental.

Sarbesh Gurung, 2, died of hyperthermia, according to the Tarrant County Medical Examiner's office. Investigators said early on that there was no sign of foul play and no visible trauma.

Sarbesh disappeared July 2 when he was home with his mother while she was doing chores and taking care of him and his older sister, police said. She turned around and when she looked again he was gone. Police said she called 911 at about 2 p.m., within four minutes of realizing her son was missing.

Despite an extensive search by police, family and neighbors, Sarbesh wasn't found until the next morning when a neighbor went to their car to go to work and discovered the boy's body inside.

It's not clear how the boy got into the vehicle. A friend of the family, Gyanendra Bohara, told NBC 5 in July that the family had an SUV very similar to the one in which the boy was found and wonders if Sarbesh wandered into it by accident.

The vehicle, according to Denton Chief of Police Frank Dixon, had dark windows, and sun shades on the windows, including at least one for children.

Still, neighbors who helped search for Sarbesh that day told NBC 5 they were surprised they didn't spot him in the SUV even with the dark windows.

"It's very surprising to me," said Amar Maharjan. "We all missed that."

With the death being ruled accidental, no charges are expected to be filed in the boy's death.

Friends said the family moved to North Texas from Nepal in 2006 so Sarbesh's father could pursue first a masters, then a Ph.D in electrical engineering at UNT.

NBC 5's Seth Voorhees contributed to this report.