Police have arrested the man who stole a car belonging to a New Hampshire couple found buried at a Texas beach, authorities said.

33-year-old Adam Curtis Williams from Logan, Utah, was arrested on Wednesday in the Mexican state of Jalisco and charged with felony theft, Kleberg County Sheriff Richard Kirkpatrick said. Williams was seen crossing into the Mexico border from Eagle Pass, Texas in the deceased's truck and RV with a female co-passenger, identified as Amanda Noverr. The police released the surveillance footage on Monday.

James Butler, 48, and Michelle Butler, 46, were found buried in a grave on Oct. 28 at Padre Island, near Corpus Christi in Texas. The couple had set up their truck and RV at the island when they went missing around Oct. 15, along with the vehicles. A missing persons report was filed by their relatives on Oct. 23.

James was a Navy veteran and the couple had married in 2015. The couple had halted in Texas on their way to Florida, reported NBC News.

"We are glad to hear the arrest has been made and await what's next," Debbie Van Loon, James’ sister, said.

Noverr was also arrested and she remained in jail in Mexico with a child, Kleberg County authorities, said. Williams was brought back to the U.S. and was held at Kleberg County Jail.

Authorities have not released the motive of killings yet. The deaths are being investigated as homicides.