. >> ross and leanna harris's seemingly picture perfect world was shattered one hot georgia day when their toddler cooper was left in a car for seven hours and died from overheating. was this a horrific mistake or murder? here with unimaginable is andrea canning. >> you're watching as a police cruiser races to an atlanta parking lot. a call for help over the radio. child not breathing. he had been found in the back seat of a hot car. every year an average of 37 children die from heat stroke after being forgotten or left behind in cars in the heat of the sun and parents pay the ultimate price for lives that are busy, distracted, sometimes overwhelming. police weren't able to save 22-month-old cooper harris is 2014 and his death in a hot car made headlines nationwide. >> new details in a tragic case we've been following. the death of a georgia toddler. >> but there was something different about cooper's story, something darker, because cooper's dad, ross harris, ended up being charged with a crime, accused not of forgetting cooper but of murdering him and his murder weapon of choice, p