After more than five months and an off-the-clock trip to Minneapolis, a St. Paul police officer reunited a man with his missing dog.

In February, Louis Christiansen, 48, reported that his dog — a golden eight-year-old German shepherd-Labrador mix named Lightning — had disappeared near his home on the 300 block of Jessamine Avenue E. He had let the dog out, but it had not returned.

Christiansen told police that he suspected a female neighbor, a transient who had shown interest in Lightning.

Sgt. Doug Whittaker, an investigator with the St. Paul Police’s Eastern District, contacted people who knew the woman. Meanwhile, Christiansen called police a few times a week to say that he was lost without Lightning and couldn’t sleep.

“I really got a sense that he was alone and this dog meant everything to him,” Whittaker said.

He could understand. When his 13-year-old dog Keno died in 2011, “It was a huge loss for myself and my family,” he said.

Finally, while off-duty a couple of weeks ago, Whittaker was called by a relative of the suspected dog snatcher who said the woman was in south Minneapolis and had a dog with her. But Whittaker would have to hurry; it sounded like she was about to leave the state.

Whittaker jumped into his truck and drove to the home, where with the help of the woman’s family he convinced her to give the dog back to its rightful owner. He promised that he would keep her posted.

The dog was initially shy and docile. But all that changed when they got back to St. Paul, Whittaker said.

Christiansen, who was waiting outside as Whittaker pulled up to the house, looked into the car window and let out a yell: “That’s him! That’s him!”

As Whittaker opened the door, Lightning “just sprang to life” and jumped out of the truck into Christiansen’s arms.

“It was really satisfying. In my career, you don’t get to see this very often,” said Whittaker, who has been with the department for 15 years.

No charges were filed against the woman.

“It was the best possible scenario,” said Whittaker, who downplayed what he did. Not so fast, said Eastern District Senior Commander Joe Neuberger.

“He really is a great example of an ambassador for the police department,” Neuberger said.

Twitter: @stribnorfleet