It seemed an unspeakable tragedy - any parent's worst nightmare. A fatal accident in the US that could have happened to anyone.
But now police are saying it may have been something much darker - and have charged the baby's father with murder and cruelty to children.
Cooper Harris, a 22-month-old toddler, died last week after being left for nearly seven hours in a sweltering car seat in suburban Atlanta, in the US state of Georgia, where temperatures had reached 31 degrees Celsius.
Witnesses saw Cooper's father, 33-year-old Ross Harris, get out of the Hyundai Tuscon SUV and frantically try to revive the boy in a shopping centre parking lot.
He called 911, screaming in hysterics, "What have I done, what have I done," witnesses say. "I've killed our child."
"It was horrible," said Artiya Eastland, 25. "That was the last thing I would ever expect to see."
Another witness, Dale Hamilton, said he initially thought the child was choking, but quickly learned otherwise.
"He was lifeless, he was in the same position as if he were sitting in the carseat," he said. "It's something that I'll remember for a long time."
Bystanders rushed to the car and administered CPR to the boy as police and firefighters arrived, but there was nothing that could be done.
With his son dead on the concrete, a distraught Harris had to be handcuffed by officers, who later drove the man to Cobb County police headquarters.
When Harris was charged with murder hours later it struck many as an overreach - trying to turn a horrible tragedy into a criminal case.
Harris claimed he had simply forgotten to drop his son off at day care while he worked at a Home Depot, and more than 11,000 signed an online petition asking the district attorney to drop the charges.
Experts said given the right circumstances, even a good parent might forget a child in a car, especially since child car seats were shifted to the back following the advent of air bags. Last year 26 deaths in the United States were blamed on children left in hot cars, and there have already been at least 13 deaths this year.
But now police think that Harris knew that Cooper had been left in the vehicle, according to a Cobb County public safety official.
They are also looking into possible inconsistencies into details provided by Harris late last Wednesday afternoon, before Cooper's body was removed from the scene.
"This is a very active, very fluid investigation," Officer Mike Bowman told The Atlanta Journal-Constitution Tuesday. "Our detectives have worked tirelessly to resolve the leads in this case. They are doing due diligence."
In other media outlets including CNN.com, Cobb police public information officer Sergeant Dana Pierce has said the case "shocks his conscience" as a police officer, but has declined to cite specifics.
In a court hearing on Thursday, Harris appeared calm as a judge told him he could not set bond because of the seriousness of the charges.
Once the police investigation is complete, it will be up to Cobb District Attorney Vic Reynolds to decide whether to seek a criminal indictment from the grand jury.
"My gut tells me is that this could be a terrible, terrible, tragic accident, it could be reckless conduct that leads to an involuntary manslaughter charge, or there could be additional facts about what happened that I don't now know that could make it a murder case," Reynolds said.
"I wouldn't be surprised if there are additional facts the police know that everybody else doesn't know," he added.
People close to Harris are sticking with him.
"Cobb County is making a big mistake," said Roger Webb, the Harris' real estate agent, who has known the family for two years. "He's a very good guy. He wanted what's best for his family."
The 33-year-old father, friends said, is successful at his IT job at Home Depot, referees at high school sports and attends church.
"Everything was going right for this couple," said Joe Saini, who rents the family their condo in Marietta. He said the family was actively shopping for a house. "They wanted to buy a house so they could have some space for their child to run around the backyard."
Harris and his wife, Leanna Harris, alternated days for dropping off Cooper at the day care, Saini said.
His wife hasn't commented publicly. When a reporter tried to reach the family by phone, the woman who answered was sobbing and said she was grateful for the support the family was receiving from friends.
On Harris' Facebook page, there are many references and photos of the boy. One shows a photo of the wispy-haired blond boy holding a children's book titled Giggle.
"Dude is growing up fast," Harris wrote.
A funeral will be held Saturday for Cooper, with a private family burial.
-Atlanta Journal-Constitution, with Stuff