A mansion, a tunnel and a vanishing man: The mystery deepened Wednesday in the case of a man accused of faking an overnight disappearance after a 2006 car crash to attract attention to his flagging congressional campaign.

Authorities believe Gary Dodds may have spent some of the 27 hours he was missing in an apartment in his 1805 mansion, which reportedly has a tunnel to the outside. Police say that when they knocked on the door, a man answered but would not let them in. When they got in hours later, he had vanished.

Dodds owns the building, the Cutts Mansion in Portsmouth, which also housed his campaign office and an apartment he rented to campaign staffer Alison Spruce.

Police went to the apartment April 6, 2006, while searchers looked for Dodds in snowy woods two towns away. After a man refused to let them in, State Trooper Joseph Ebert said he and other officers stood watch until Spruce returned home and opened the door to the then-empty apartment.

"There was a very low chance that someone could leave the apartment without being seen," Ebert said.

Spruce testified that she was in and out of her apartment that day, leaving to attend college classes, take a walk and visit her parents. She was not asked to explain the man's voice police reported hearing but said she would have known had anyone been in the apartment.

"I would like to think so. I am very meticulous," she said. "I would like to think I'd know if someone had been there."

Dodds, 43, is on trial in Strafford County Superior Court on charges including falsifying evidence, which carries a possible seven-year sentence.

Prosecutors say Dodds faked his story about crossing an icy river and spending a night in the woods. They say he soaked his feet in cold water for hours as part of a ploy to attract attention to his flagging campaign for the Democratic nomination in the 1st Congressional District.

Defense lawyers call that preposterous. They argue that Dodds has been wrongly accused by law enforcement officials to deflect attention from their bungled search-and-rescue effort.

In court, no one has mentioned a tunnel at the mansion, which was built in the old seaport of Portsmouth by ship's captain Edward Cutts. But in 2000, Dodds told the Portsmouth Herald there was one for a feature story the paper did on Dodds and his wife renovating the building and trying to learn its history. He said the tunnel ran from the mansion to a cove.

Dodds' car struck and went over a highway guardrail in Dover; he said he swerved to avoid a deer and remembered little after the crash other than wading through the river and wandering through the woods in a daze.

Authorities estimate they spent $18,000 searching for Dodds with teams assisted by dogs and a helicopter. Dodds was found the next night, a mile from the crash scene under a pile of leaves, fading in and out of consciousness and missing a shoe.

Dodds was never considered a contender in the primary, which he lost to Carol Shea-Porter. She defeated Republican Rep. Jeb Bradley in the general election.

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