HENDERSON, Texas – A Frisco couple died from carbon monoxide poisoning at an RV park in Rusk County over the weekend, a medical examiner has ruled.

Matthew Thomas Rawley, 43, and his wife, 34-year-old Erica Nicole Rawley, were to have checked out of Gator Run RV park Sunday morning, said Sgt. Viki Penny of the Rusk County Sheriff's Department.

When they didn't, their family called local authorities.

Penny said deputies were dispatched to the RV park, about 15 miles southeast of Longview, on Sunday night and found the couple dead in their trailer.

The Southwestern Institute of Forensic Science in Dallas confirmed the cause of death was carbon monoxide poisoning.

Sgt. Penny said the likely source of the carbon monoxide was the heater in the couple's RV.

Staff writer Aida Ahmed contributed to this report.