The police are investigating how the twins got into the vehicle. Their parents have not be arrested on suspicion of neglect.
An autopsy has been conducted, and has revealed that the death of the twins were heat related.
According to People, no charge has been given against the parents of the deceased. The focus will be on how the twins got into the vehicle, a spokesperson for the police revealed.
"Our investigation will focus on how the kids ended up in the pickup truck, and whether it was due to someone's actions or was accidental,"
"We've yet to determine whether anything occurred here that could warrant criminal charges."
Report has it that the death of the twins came three weeks after Oliver returned from the hospital, having received treatment for unspecified injuries.