By Joe Sterling
(CNN) -- It sounded like a tragic accident.
A young father in suburban Atlanta said he was horrified to discover after leaving work last week that he had left his toddler strapped into his car seat on a day of sweltering heat.
The toddler died.
On Wednesday, investigators released new information that sheds light on why they charged Justin Ross Harris with murder and cruelty to a child in the death of his son.
Authorities in Cobb County, just north of Atlanta, released an arrest warrant that says Harris returned to his car and opened the driver's side door several hours before he said he found his son in the backseat.
Their decision to arrest Harris has triggered vigorous debate, with many people saying police should not have charged the father after what seemed to be a heartbreaking accident.
Several hundred people have signed an online petition urging Cobb County District Attorney Vic Reynolds to drop the charges.
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