Kevin Rowson and Melissa Long

WXIA-TV, Atlanta

ATLANTA — A Georgia father was booked on murder charges early Thursday after leaving his son all day in a hot car.

Justin Ross Harris, 33, of Marietta, Ga., went to work at around 9 a.m. Wednesday with his 22-month-old son in the back seat of his sport utility vehicle, forgetting to drop him off at day care, said Sgt. Dana Pierce of Cobb County Police. As he was driving home around 4 p.m., he noticed that his son was still in his child seat, unresponsive.

He pulled over at a shopping center parking lot and tried to perform cardio-pulmonary resuscitation, but the child, whose name was not released, was pronounced dead at the scene.

"It is a very fine line sometimes between neglect and negligence ... and whether that negligence reaches the level of criminal prosecution," Georgia Gov. Nathan Deal said Thursday.

Police had to restrain Harris because he was so distraught and took him into custody for questioning then.

Harris is being held without bond in Cobb County Jail on charges of murder and cruelty to children, also a felony, according to online records from the Cobb County Sheriff's Office and the warrant for his arrest. He is expected to have a court arraignment later Thursday.

The toddler's death was the second this week of a child in a hot car. On Monday, a 9-month-old girl died in Rockledge, Fla., after her father forgot to drop her off at her grandmother's house, leaving her in the back seat of his pickup truck for several hours as he worked at his job as a telephone solicitor for the Fraternal Order of Police.

As of Thursday, no charges had been filed against Steven Lillie, 31, of Cocoa, Fla. Rockledge Police say they still are investigating the death and allowing Lillie and his girlfriend, the child's mother, to grieve the loss.

"She's been in the car for hours, and I absolutely forgot about her," Lillie said during a 9-1-1 call Monday to police dispatchers. "She's not alive."

The Florida Department of Children and Families also is reviewing that case. An autopsy has been completed, but preliminary findings have not been released.

The National Safety Council recommends that parents leave something in the back seat of their vehicle that they need for work or their errands, such as a briefcase, purse or cellphone, to serve as a reminder of the child in the car seat.

On the day after Memorial Day, Georgia's governor announced a campaign called "Look Again" to make parents aware of the dangers of heat stroke for children and pets as the weather warms.

"This is a warning. In only minutes, the inside of your car can become a death trap for a child," Deal said in one of the public-service announcements. "You can be a hero. You can prevent a tragedy."

On Wednesday, the high in the Atlanta area was 88 degrees. And though it was around 70 degrees in the morning, temperatures can rise quickly inside a closed-up vehicle — 20 degrees in 10 minutes, 30 degrees in 20 minutes and 40 degrees in an hour.

Children are more susceptible than adults to heatstroke, when body's internal temperature rises to 104 degrees. And unless any victims of heatstroke are cooled down quickly, they can die.

In 2013, 44 children across the USA died as a result of vehicle-related heat deaths, according to KidsandCars.org, a nonprofit child safety organization that monitors news sites and police reports involving children and vehicle accidents. Statistics also show that 12 other children in the U.S. died so far this year after being left in vehicles — and summer doesn't officially begin until Saturday.

Contributing: J.D. Gallop, Florida Today; and Devin Fehely and Donna Lowry, WXIA-TV, Atlanta