An arrest warrant has been issued for a man suspected of stealing a car that belonged to a New Hampshire couple found buried at a South Texas beach.

James and Michelle Butler. Courtesy Stephanie von Loon

The Kleberg County Sheriff's Office in Kingsville, Texas, said Tuesday that Adam Curtis Williams, 33, is wanted on felony theft charges.

Adam Curtis Williams. Kleberg County Sheriff's Office

Authorities identified Williams as the man seen in a surveillance photo released Monday crossing the border into Mexico in a car that belonged to James and Michelle Butler, whose bodies were found in a shallow grave in Corpus Christi last week.

“This person is considered armed and dangerous,” Kleberg County Sheriff Richard Kirkpatrick said at a news conference Tuesday, adding that a woman traveling with Williams, Amanda Noverr, is a person of interest in the case.

Authorities believe Williams and Noverr might have had contact with James Butler, 48, and his wife, Michelle, 46.

The Butlers vanished Oct. 15 while camping on Padre Island, near Corpus Christi. They were reported missing on Oct. 23 after friends and family lost contact with them. Their bodies were found in a shallow grave in Corpus Christi on Oct. 27.

Adam Curtis Williams crossing the border into Mexico in a car that belonged to James and Michelle Butler. Kleberg County Sheriff

Officials have said the Butlers' deaths are being investigated as homicides. The sheriff's office said Tuesday it is withholding the causes of death.