FREMONT — In 1844, a man named George Thompson fell in love with a woman named Catherine Hamler.

Thompson wanted to marry the 18-year-old Hamler, but by historical accounts, the feelings were not mutual. Thompson repeatedly proposed, but she declined each time. Seemingly fed up with rejection, Thompson eventually shot and killed Hamler at the Exchange Hotel in Bellevue. He was sentenced to be hung on the gallows where the present-day Sandusky County Common Pleas Courthouse resides.

Before their execution, criminals like Thompson were held underground in a dark, windowless prison known as the dungeon. Thompson is one of two known murderers exposed to those dungeon conditions for an extended period, and Sandusky County Convention and Visitors Bureau Travel Event Specialist Katherine Rice said those two killers are one reason the dungeon is said to be haunted.

“They were part of the catalyst for the dungeons to be completed,” said Rice of the two murderers.

In his 1909 book, “Twentieth-Century History of Sandusky County, Ohio,” Basil Meek gives an account of county jails. Meek wrote that Thompson twice escaped from the county’s first primitive jail in 1826, which in part caused county commissioners to look into a more secure means of incarcerating criminals.

While the county constructed its first full-scale jail in the 1840s, the dungeon served as a temporary holding place for criminals. That did not last long.

“This dungeon was a damp and dismal place, more in keeping with an age of barbarism than that of a Christian civilization,” Meek wrote. “(The dungeon) so shocked the humane sense of the public that its use as a place of confinement for prisoners was not long continued.”

With its windowless, three-foot thick stone walls and constant surveillance by the sheriff himself, the dungeon was a place few, if any, escaped from.

“There’s a general air of creepiness down there,” Rice said. “The low ceilings and the tight quarters all lend themselves to something dark and foreboding.”

Rice said the dungeon’s history could explain why some believe it to be haunted. She also offered another possible explanation.

“This is not substantiated and it is local folklore, but it is believed very strongly that (the Sandusky County Historical County Jail) was used as a stop on the Underground Railroad,” Rice said.

Rice said the dungeon’s unsanitary conditions, Thompson and another murderer said to have ended his own life in the dungeon and the possible lingering feelings of escaped slaves all could have contributed to claims of paranormal activity inside the dungeon.

The visitors bureau began offering dungeon tours in November, and Rice said the tours have been well received. Several tourists questioned whether the dungeon was haunted, so Rice had two independent paranormal research groups investigate the building and present their findings in March.

Both groups reported finding evidence the jail was haunted. On Wednesday, the bureau announced a new attraction called “Dungeon Descent: An Adventure into the Paranormal,” which takes groups on a guided investigation of the dungeon with a paranormal research team.

Rice stressed the paranormal investigation would not include the jail history or background offered on the monthly dungeon tours and Jailhouse Rocks program.

Experts will brief the tour groups on procedures and equipment used in the investigation before they disband into groups of three to explore the dungeon, gallows and jail cells. The evening concludes with a group sit-down, where members can share their findings with one another over a pizza.

The event lasts from 8:30 p.m. until 2 a.m. Rice said visitors are encouraged to bring their own cameras and equipment, but cellphones will be banned because of the possibility of manipulating or creating fake paranormal evidence.

Tickets cost $20 per person and sales begin April 22, first-come, first-served. The event is open to groups of 25, and Rice said there will be three tours this year.

The investigation is not recommended for people who are pregnant, have heart problems or are younger than 15.

Call the bureau at 419-332-4470.