PARIS — Dunkin, her nine-week-old Beagle/Lab, was missing, almost certainly stolen from her truck Thursday in South Paris.

“I had myself completely convinced I was never going to see him again,” said Jessica Smith of Bethel. “It’s not very often that a stolen dog returns, or is returned, or is found.” But Dunkin is back home, thanks in part to Facebook.

Dunkin has been Smith’s commuting companion since joining the family just before Easter.

“We have food and water in the back of the truck and all his toys. That dog goes with me everywhere. “If I leave this house and don’t take him, he gets mad at me,” Smith said. “He’d rather be in that truck then anywhere else.” On the day he disappeared Dunkin had come along when Smith drove to South Paris to attend an adult-ed math class at the Fox School.

When she went in to class, she left him in the truck.

At the time, Smith said, she thought the truck could not be locked, because of a key problem.

When she went out on her break, to take Dunkin out to go to the bathroom, he was gone.

“There was no way he got out on his own,” Smith said. “I knew he was taken.” She called the South Paris police.

When going into class earlier, she had noticed a car parked next to the truck, red with distinctive black markings on the doors.

She mentioned that to the police, who advised that if she saw the car again to take down the license plate and call them back.

“So I rode around looking for it,” Smith said.

She also stopped in at the Norway Veterinary Hospital and the local animal shelter, where she left descriptions of Dunkin.

When she returned home, she went to the Facebook page of Oxford Hill Swap and Save, and posted his picture and a description.

About 7 that evening a women replied: “I know where your dog is. Call.” Smith did, “and she told me who she thought had taken Dunkin.” She called Dispatch.

An officer called the woman. He was already familiar with her, and knew that she owned a car matching Smith’s description of the one that had been parked next to her.

The woman at first denied having a dog, then admitted to having one, but said she had found it wandering.” Unconvinced by the changing stories, the officer told her: “We know you have the dog. You need to meet me within the hour with him or I’m going to have to put you in jail.” She did, and was summoned for possession of stolen property.

“Since they couldn’t prove she had taken it,” Smith said.

She and a friend met the officer at the Lake Store, and Dunkin came home.

Smith said she later learned that the truck could, in fact, be locked, but for now she plans to leave Dunkin at home, where friends can keep an eye on him.