RALEIGH, N.C. (AP) — The car where three Marines died of accidental carbon monoxide poisoning in North Carolina in July had unconnected and rusted exhaust pipes, according to autopsy findings released on Wednesday.

The Pender County Sheriff’s Office said months ago that autopsies performed on Camp Lejeune lance corporals Tanner Kaltenberg, Merax Dockery and Ivan Garcia determined that they died of carbon monoxide poisoning, which can happen from car exhaust.

The new reports, which said there were no obvious signs of suicide, foul play or drug use, confirmed that as the probable cause of death.

But the reports from the North Carolina Office of the Chief Medical Examiner provided additional information regarding the circumstances surrounding their deaths. The Marines were found dead the morning of July 23 at a convenience store parking lot in Hampstead, in the southeastern part of the state. The 2000 Lexus sedan belonging to Garcia was equipped in an unsafe manner, the reports suggested.

The car “had been modified in a way that caused multiple large defects in the exhaust system,” according to the reports, which say the car had been “lowered” and the exhaust pipes were rusted and not connected.

“It appeared that exhaust from the vehicle would have been released under the passenger cabin of the vehicle and not at the rear bumper,” the reports said.

The Marines’ blood had concentrations of carbon monoxide that ranged from 24% to 27%, according to the toxicology reports.

The findings led to the determination that the deaths were an accident.

A sheriff’s spokesperson didn’t immediately respond to a Wednesday phone message seeking further information.

Deputies found the three men about 30 miles (50 kilometers) southwest of Camp Lejeune, after the mother of one of the Marines reported her son missing.

Surveillance video from the gas station shows the Marines parked the car in the early hours of July 22 and were never seen exiting the vehicle, the medical examiner’s office said. The car’s windows were tinted, and although the car was unlocked and the ignition was turned on when authorities found the vehicle, it wasn’t running, according to the reports.

Kaltenberg, of Madison, Wisconsin, was 19. Both Dockery, of Seminole, Oklahoma, and Garcia, of Naples, Florida, were 23.