Passengers in a car that crashed and killed three people had been drinking and inhaling nitrous oxide before the incident, a friend told police.
Driver Rafel Jeanne, 24, and passengers Darcy Ross, 21, and Eve Smith, 21, were killed in the crash, while two others, Sophie Russon, 20, and Shane Loughlin, 32, were injured. .
The fatal accident occurred when the Volkswagen Tiguan came off a roundabout on the A48 near the St Mellons area of Cardiff and crashed into a small grove of trees on March 4 this year.
The vehicle was discovered around two days later, on March 6.
The time it took for Gwent Police and South Wales Police to find the group, who had been reported missing by family members, is the subject of an ongoing investigation by the Independent Office for Police Conduct.
The friends had been out for a night out at The Muffler social club in Maesglas, Newport, on March 3 and traveled just under 40 miles to Trecco Bay Caravan Park in Porthcawl, where they reportedly spent some time in one of the caravans.
It is understood that a neighbor complained to the park security booth about the noise they were making.