NEW YORK • A 1787 first-edition book signed by Thomas Jefferson, the third president of the United States.

A rare copy of a book written by another US president: The Journal Of Major George Washington.

And a version of Isaac Newton's Principia, noted among the most influential books in science, said to be worth US$900,000 (S$1.2 million).

The archivist who oversaw a special collection of rare books at the central library in Pittsburgh walked out of the building with these and others - sometimes in plain sight.

He then sold them to a local bookstore owner in a scheme that lasted nearly 20 years, US authorities said.

The library archivist, Gregory Priore, 61, and the bookstore owner, John Schulman, 54, were arrested on Friday on numerous criminal charges, including theft and criminal conspiracy, authorities said.

They are accused of trafficking several hundred rare books, maps and other items worth more than US$8 million (S$11 million) in total, records showed. More than US$1 million worth of items, including the Newton volume, have been recovered.

Even in the niche world of rare-book dealers, the value of the items stolen is stunning, said Mr Michael Vinson, a dealer based in New Mexico who is a member of the Antiquarian Booksellers' Association of America. "This is a huge deal," said Mr Vinson, noting that most rare-book dealers have annual sales of between US$500,000 and US$1 million.

The partnership between Priore and Schulman began in the late 1990s, according to an affidavit filed by the Allegheny County District Attorney's Office, which investigated the case.

Priore told authorities that he approached Schulman about selling some items in the library, but that Schulman later "goaded" him on.

Priore said he used the money to stay "afloat" and help pay tuition for his four children. "I loved that room, my whole working life, and greed came over me," he said.

NYTIMES