Investigators searching for a pair of grandparents who went missing in Georgia last week have discovered the unidentified bodies of a man and a woman as well as a vehicle owned by the missing couple, according to police.

“It’s not the outcome we had hoped for, but obviously it’s one we have to deal with,” Telfair County Sheriff Chris Steverson told reporters during a press conference on Monday afternoon.

Steverson said the vehicle — a 2003 GMC Envoy — was found in a shallow body of water, but at a separate location from the two bodies, which are expected to undergo autopsies on Tuesday.

“The bodies were not submerged in water,” he said. “Only the automobile was in the water.”

A suspect who is believed to have been the last person to speak with Elrey “Bud” Runion, 69, and his wife June Runion, 66, is now in police custody.

Ronnie “Jay” Towns — who had one active warrant for making false statements to investigators and another for criminal attempt to commit theft by deception — turned himself in to authorities on Monday morning, according to Steverson. Police said the bodies were discovered at a location that was “not far” from property owned by the Towns family.

The Runions were last heard from on Thursday, shortly before they planned to meet a person who’d responded to their Craigslist posting seeking a 1966 Ford Mustang convertible.

Steverson noted earlier that the 28-year-old Towns has no criminal background and “comes from a good family.” On Tuesday, according to the Macon Telegraph, the sheriff told Fox News: “As you can imagine, the family is as shocked as the rest of the community that he’s been named as a suspect in this case.”

Theft, Steverson said, was the apparent motive, according to the Telegraph.

“We have a mountain of evidence to go through in the coming days and we’ll go from there,” Steverson said, according to the Telegraph. “But, obviously we believe the Runions were coming to make a purchase of a vehicle.”

Details of Towns’s alleged interaction with the Runions remain unclear, but Steverson said police interviewed him early in their investigation and that the information he provided “did not corroborate” with their investigation,” according to WMAZ.

On Thursday, the Runions told relatives they were headed from their home in Marietta, Ga., to Telfair County, three hours to the south. There, they planned to meet with the seller of a Ford Mustang who had responded to their Craigslist post, according to police.

The Runions were supposed to return home Thursday evening, but they haven’t been seen or heard from since, according to police. Family members grew concerned when the pair didn’t show up to babysit their grandchildren the following day, according to ABC affiliate WSB

“He was excited about the car,” Stephanie Bishop, one of the couple’s daughters, said of her father. “He had one when he got back from Vietnam.”

“During this heartbreaking time I ask that you keep the family and friends in your thoughts and prayers,” read a statement posted Monday on the Find Bud & June Runion Facebook page.

A later posting quoted scripture and added: “Bud & June had an amazing love. They loved God and that is evident in how they lived.”

Bishop told the station her father had recently posted an advertisement on Craigslist seeking a 1966 Mustang and a seller responded and even included a photo.

The couple left home in a champagne-colored 2003 GMC Envoy around 2 p.m., according to police.

Family members said that Bud Runion, a military veteran, was not naive about personal safety, and that the couple left with their cellphones and chargers, though he had turned off his iCloud settings.

Investigators have linked the number the couple called to set up the meeting to a disposable cellphone, according to police.

Telfair County authorities said that a search of local hotels and hospitals turned up nothing.

Authorities declined to comment about whether the couple’s bank accounts were accessed or whether the Mustang’s owner was a legitimate seller, according to WSB.

Family members told WSB that they are very worried but focused on the task of locating their loved ones.

“If someone has taken them, we have forgiven that person, because God tells us to love and forgive,” another of the couple’s daughters, Virgina Owens, told the station.

Craigslist’s “personal safety” page says that among the billions of “human interactions facilitated” by the site, the incidence of violent crime is “extremely low.”

However, in addition to telling users to carry a cell phone with them during transactions, Craigslist also warns buyers and sellers: “Do not meet in a secluded place,” “be especially careful when buying/selling high value items” and “consider having a friend accompany you.”

[This post has been updated.]