Dan Marsula, Post-Gazette

During a visit to the 19th-century McCue Mansion, Rose St. John, co-founder of Beaver County Ghost Hunters, sensed the presence of a ghost.

"You can feel that spirit energy," she said of the historical home in Monongahela, sometimes called the "Demon House." The house, privately owned but open for tours, is believed to have been built in the late 1800s on an abandoned burial ground for American Indians.

The Beaver County Ghost Hunters, a nonprofit dedicated to delving into the paranormal, often visits such sites.

Of her recent experience, Ms. St. John, of Rochester, said she felt as if she were in a daydream.

"She seemed to be an upstanding member of the community," she said of the apparition's regal composure.

Ms. St. John said she got the impression that the ghost once lived in the house.

Tomorrow, Friday the 13th, Ms. St. John, 50, will discuss such otherworldly experiences in a presentation at 7 p.m. in the South Park Township Library, 2575 Brownsville Road.

She also will sign and sell copies of the group's self-published, "Ghostly Encounters I" and "Ghostly Encounters II," which recount their local adventures in homes and at historical sites.

The event is open to adults and children age 12 and older. Those who come must register, by calling 412-833-5585.

Donna Neiport, the library's adult services coordinator, said she arranged the presentation as an expansion of the library's popular collection of the occult and ghost stories.

Besides, it is Friday the 13th, a day tradition says is a time for exploring the supernatural.

The local ghost hunters will share tales and photographs of favorite haunting experiences and will display the tools that no serious ghost hunter should be without. They include an electromagnetic field detector, infrared motion detector and an infrared thermometer, which are said to pinpoint cold spots that could signal an unearthly presence.

Members use cameras, disposable and digital. They buy all the equipment themselves.

The informal group comprises about 20 people of all ages and from all walks of life, including a minister, from Allegheny and Beaver counties.

Members said they sometimes capture messages from beyond the grave by using the services of a medium, a person who says he can bridge the natural and supernatural worlds.

Ms. St. John said her interest in the paranormal began as the child of a superstitious mother. She said as she grew up she developed presentiments, or feelings that later prove to be true, that something is about to happen.

That led to her opening a shop, Lilyrose Curios, which dealt with the supernatural. The store has since closed.

When some teenage girls asked her to take them ghost hunting for a school project about five years ago, the group Beaver County Ghost Hunters was started.

Today, those young women are part of the ghost hunters team that will, free of charge, investigate rumored ghostly goings-on at private homes and public places.

"We don't go to cemeteries because we feel it is an invasion," Ms. St. John said.

Donations from presentations and lectures fund the group's annual conferences, such as their Beaver County Paranormal Conference in Monaca on Sept. 29-30.

Ms. St. John said what started as fun quickly developed into a serious way to help the living who have questions about spirits, as well as those who have passed on.

"A lot [of spirits] don't know they are dead," she said.

She would like to hone her craft and help police solve cases.

The team visited Demon House on a recent night when there was a full moon and, in addition to doing their thing, were part of a commercial for the on-demand service of Comcast.

The group conducted a seance that night, and members said they made contact with a spirit named Walter, whom they described as a short, chubby banker, and Cassidy, whom they thought to be a young servant.

Ms. St. John said that, contrary to the images of flighty heroines in horror movies, such encounters don't make her want to run.

"I feel very welcome in haunted houses," she said.

For more information about Beaver County Ghost Hunters, and for more on the history, fees and how to visit the Demon House, see beavercountyghosthunters.com.