Last month, Richie Gray of Hartsville, South Carolina, said he forgot to drop off his daughter, Sophia, at day care -- and left her sleeping in the backseat of his car in 90-degree heat.
She did not survive. She was just 13 months old.
"It's so easy for the child to go to sleep and you not realize they're still in there, because your brain is on autopilot,” Gray told NBC News.
It happens all too often.
According to KidsAndCars.org, there have been almost 400 children who have died in hot cars in the last decade. On average, that’s 38 per year -- or one every nine days.
Last year, there were 44 deaths. So far this year, there have been 13.
Even if it’s just 80 degrees outside, the temperature inside a car can skyrocket to about 120 degrees in less than an hour.
In the past two months: 4-year-old Bella-Rose Lindstrom died in Texas; 2-year-old Alejandra Hernandez-Mendoza died in Sarasota, Florida; and just this week, near Orlando, police said another child was killed when her father, Steven Lillie, left her inside his truck.
"She's been in the car for hours and I absolutely forgot about it," Lillie told the 911 dispatcher.
Prosecution has varied greatly state-by-state and case-by-case.
Police in suburban Atlanta are investigating how a 22-month-old boy ended up in the backseat of a car for seven hours. His father, Justin Ross Harris, 33, of Marietta, Ga., is charged with murder but has pleaded not guilty.
Safety advocates, such as the National Safety Council and Safe Kids Worldwide, stress that parents should leave something they need in the backseat, like a purse, briefcase or cell phone. At the very least, they can leave the child’s diaper bag in the front seat as a visual reminder.
In South Carolina, Richie Gray said he wanted his story to serve as a reminder to all parents. He’s been passing out pink elephant stickers for parents to put in their car windows to make sure they never forget about their child in the backseat.
Gray has been charged with unlawful conduct towards a child –- but he said his child’s death was a tragic accident.
"There's a massive amount of guilt that you feel,” he said. “As the father, you're the protector, you know? You're daddy… It's an unimaginable loss."