The next day, Gricar’s Mini Cooper was found in a parking lot in Lewisburg, about 50 miles from his home in Bellefonte. Gricar’s cellphone was in the car, but not his laptop, wallet or keys, which were never recovered. Months later, the laptop was found in the Susquehanna River without its hard drive, which was discovered later. It was too damaged to yield any information. On the fourth anniversary of his disappearance, investigators revealed that a search of his home computer yielded a history of Internet searches for phrases like “how to wreck a hard drive,” according to a report at the time in The Centre Daily Times.

When Gricar disappeared helicopters, dive teams and patrol cars were deployed, and the F.B.I. was brought in. Reports of Gricar turning up in Illinois, Ohio, Michigan, Maryland and other states proved to be dead ends.

So what happened? Friends and colleagues say Gricar was not the type to walk away. His bank accounts were not touched after he disappeared, he had no other sources of income and he had no major debts, said Robert Buehner Jr., a friend and the district attorney in Montour County. Though divorced twice, he seemed happy with his girlfriend and close with his daughter. Gricar had already announced that he was retiring at the end of his term.

“He was absolutely looking forward to his future,” Buehner said.

If Gricar committed suicide, Buehner added, he would have wanted the body to be found. Foul play is the next possible conclusion. By the nature of their jobs prosecuting criminals, district attorneys end up having many enemies. But no credible suspects have emerged.

“I don’t think you’ll find too many district attorneys who disappear,” said Ken Mains, a detective who works on cold cases in Lycoming County. “D. B. Cooper, Amelia Earhart, Jimmy Hoffa, until a body is found, there are going to be conspiracy theories.”