BANGOR, Maine — Supporters of the Bangor Public Library on Thursday thanked a downtown merchant for his role in saving an irreplaceable collection of posters and portraits, many dating back to the Civil War.

Friends of Bangor Public Library, a volunteer organization geared toward supporting and raising funds for the library, recognized Paul Zebiak with a plaque and show of appreciation during a ceremony at the library.

“If not for Mr. Zebiak, we would have been out a lot more than a financial loss,” said library director Barbara McDade. “These items are history.”

In September, Russell Graves, 28, was sentenced to two years in prison with all but six months suspended for stealing an estimated $31,000 worth of Civil War, World War I and World War II memorabilia from the library’s collection.

Zebiak said he was glad he was in the right place at the right time, with the right base of knowledge to recognize that the items likely belonged to a more reputable collector in the area.

Earlier this year, Graves admitted that he took 75 Civil War-era cartes de visite, small 2½-by-4-inch portraits that were extremely popular during the war, and about 50 posters from World War I and World War II. All of the stolen items were recovered after his arrest.

Graves was working as a janitor under the city’s workfare program when the thefts were discovered Feb. 25, according to a previously published report. Workfare is a system under which general assistance recipients work for the city or nonprofits in return for receiving their subsidy.

“It was a theft of trust, and it was a theft of irreplaceable materials,” McDade said.

The thefts were discovered after Graves tried to sell some of the items at Maritime International, a buyer and seller of collectibles located about a half block away from the library. Zebiak owns Maritime International.

“Something didn’t click with his story,” Zebiak said before Thursday’s ceremony.

Graves tried to sell him some items shortly before closing time one evening, but Zebiak didn’t purchase the items because Graves lacked valid identification.

Aware that the Bangor Public Library has a collection of similar war memorabilia, Zebiak contacted the library after the man left his store. Library staff checked the archives and confirmed they were missing a large number of items from their collection.

It wasn’t Zebiak’s first time helping to retrieve items of historic value from the hands of a thief. Back in 2001, another thief lifted about $30,000 worth of rare books, papers and prints from the library and attempted to sell them to area shops.

Bangor Police Chief Mark Hathaway said Thursday that Zebiak’s information was integral in solving that case, again after the thief tried to sell him stolen materials.

Follow Nick McCrea on Twitter @nmccrea213.