CORPUS CHRISTI, Texas — Authorities say police in Mexico have arrested 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

Kleberg County Sheriff Richard Kirkpatrick confirmed on Wednesday that Adam Curtis Williams had been arrested by authorities in the Mexican state of Jalisco on felony theft charges.

Authorities believe the 33-year-old Logan, Utah, man and Amanda Noverr might have had contact with 48-year-old James Butler and 46-year-old Michelle Butler. They released a surveillance photo of Williams and Noverr crossing the border into Mexico in a car belonging to the Butlers.

James Butler's sister Debbie Van Loon told WMUR-TV in Manchester, New Hampshire: "We're glad to hear the arrest has been made and await what's next."

Officials say the Butlers' deaths are being investigated as homicides. Their bodies were found last week in a shallow grave on Padre Island, near Corpus Christi.