Three years ago, police investigated Tyler Cestia for negligent homicide after he left his 2-and-a-half-year-old son, Thomas, in his truck at work on a hot summer day. 

"In my mind, I remember thinking, 'well, I don't remember walking in the sitter's house to drop Thomas off; I don't remember that,'" said Cestia. "I just said to myself, 'it can't be. There's no way.'"

Cestia said a confluence of circumstances created the perfect storm that June morning. He wasn't originally supposed to drop off Thomas, and the toddler sat in his brother's car seat behind the driver — out of sight. Cestia said he was also recovering from COVID, which gave him brain fog, and his mind was preoccupied with an audit at work. Six hours into his workday, he realized he never dropped off his son that morning.

"I ran out to the car to see and, unfortunately, my worst fears were realized," he said.

His wife Pamela got the call and frantically raced to the office parking lot.

"I kind of didn't know how fast children could pass in the car," Pamela said. "So, I drove like a maniac to Tyler's work and then just saw Thomas, and he was gone. I just broke down after seeing and knowing what happened."

It was a moment she had trouble processing — a moment she said she couldn't imagine ever happening to her family.

"I think before this experience, I was a little judgmental on that and thinking that how do people leave their kids in the car and forget their children," said Pamela. "I think, now, that anybody can leave their kids in the car and forget them. It can be, something else on your mind at the time, a change in routine, that it can happen to anybody."

Police ruled the death an accident.

Summer heat turns deadly

The National Oceanic and Atmospheric Administration warns much of the U.S. will see above-average temperatures and dangerous heat this summer. For some children, it has already become deadly.

Last month in South Carolina, a 3-year-old became the first hot car death of the year, after he crawled into the back of a vehicle and got trapped.

A few weeks later in West Virginia, a 3-month-old baby died inside a car after police said it appeared the child was inadvertently left there while the parent was at work.

According to data from advocacy group Kids and Car Safety, on average, 38 children die each year from heatstroke inside a vehicle. Over the last three decades, more than 1,000 children have died in these incidents.  

A CBS News data analysis shows 83% of all hot car deaths over the last six years happened between May and September — at least one death each week during the sweltering summer season. It's not just happening in states with the warmest temperatures. The breakdown reveals a hot car death reported in nearly every state. 

"Quite frankly, we're surprised it doesn't even happen more often," said Janette Fennell, co-founder and president of Kids and Car Safety.

Fennell said after the introduction of dual front airbags, parents moved infant car seats to back seats for safety reasons. It was then, she explained, that they began to see the increasing trend of parents forgetting their children in vehicles.

"During that transition, nothing was done to change the way we notify people if children are left alone in vehicles," she said. "So, it's a direct correlation of putting the kids in the back seat out of sight, out of mind, and then the number of hot car deaths just keeps going up."

Turning to technology

Over the last few years, companies have created technological advances to help reduce the chances of children being left in cars and dying. Automakers have been working on safety systems that can provide alerts to remind drivers to check for children who may still be in vehicles, or even detect a child left behind.

"We've seen a tremendous amount of innovation just in the last few years, following a commitment by automakers in 2019, to integrate these technologies into all new vehicles," said Hilary Cain, with the auto industry trade group Alliance for Automotive Innovation.

The 2021 infrastructure law included a requirement for all automakers to install an audio and visual rear seat reminder alert in all new passenger vehicles beginning with model year 2025. Most have already done this — voluntarily.

Fennell argues law and the technology don't go far enough.

"What's written in the law is sort of just the driver reminder system," she said. "We've been working with the National Highway Traffic Safety Administration, and they know that that's not really an adequate solution. In fact, we as an organization have documented deaths of six children who have died in cars that have just that reminder, so obviously it's not effective."

The Cestias had that very technology in their truck when Thomas died.

"The way we thought all along how the technology worked in the truck was based on weight," said Tyler Cestia. "You know, you have a child in the seat, [from] the weight."

While some vehicles do have weight sensors, the Cestias' truck used door logic technology that only warns the driver to check the back seat at the end of a trip if a back door has been opened and closed at the beginning of a trip. Tyler described the alert as the same as the beep that reminds you to put on your seatbelt.  

"We had a false sense of security with the rear seat reminder," said Pamela Cestia.

NHTSA provided written responses to questions from CBS News, which said: "NHTSA is researching technology and solutions that can provide greater safety benefits beyond the mandated minimum, including detection technology for unattended occupants." 

Radar technology

The Cestias are advocating for the administration to require more advanced technology like radar systems that don't simply issue reminder alerts but detect movement. They can even sense the breathing of a baby.

"So, the difference between this and a typical rear alert reminder… is that this actually detects the presence of life," explained Tyler
Warga, with automotive technology supplier Bosch. "It's actually doing the displacement in a child's chest, and so you're talking millimeters in terms of the type of movement it can detect."

Some of Hyundai's Genesis models offer what it calls an advanced rear occupant alert system, which utilizes both a rear seat alert and radar technology. It also sends out warnings to parents even when they're not in the vehicle.

"If the sensor detects movement within the vehicle, you're going to have the horn go off and you're also going to get an alert on your smart app," said Stephanie Beeman, manager of vehicle safety, compliance and regulatory affairs for Hyundai America Technical Center.

We asked the Alliance for Automotive Innovation why it isn't committing to the radar technology some experts consider the gold standard for safety.

"The automakers want to provide technologies that best meet the needs of their customers, and so there are a range of options for them to do that, and radar technologies would be one of those options," Hilary Cain said. "There are a lot of people who purchase vehicles today that do not have children and may not need or want these systems. Since these systems will be standard on all vehicles, there will be a cost, you know, and reflected in the price of the vehicle for the technologies. So, providing a range of technologies may give purchasers who are not interested in the technology, don't need the technology, a lower price point than otherwise they would have."

According to government documents, the upgrade to radar would cost car buyers as little as $20. 

"The companies are going to go this way," Cain said. "They're already going that way. We're just – you got to give it time for them to do it."

But Pamela and Tyler Cestia believe if the radar technology had been in their truck three years ago, Thomas would still be alive.

"The gold standard should be met," said Tyler Cestia. "There's better technology that's far superior to the existing technology, and there's no reason for another parent to go through it."