Prince William County police said they think the death of a 2-year-old boy who was left in a car seat in the family minivan Friday was accidential.

Police spokeswoman 1st Sgt. Kim Chinn said the investigation is ongoing and no charges have been filed.

Chinn did not say who was responsible for leaving Ryan Murphy in the van in front of the family’s home in Bristow. “We’re putting that together now,” Chinn said.

The child was discovered at 4 p.m. Friday, and was last seen alive at 9 a.m., according to police. Police said the cause of death may have been heat-related.

A man who answered the door at the family’s home on Gentle Shade Drive declined to speak to a reporter Saturday. The short driveway where the child was found in the van does not have shade. Temperatures were in the 70s and low 80s Friday.