WILLIAMSPORT, Pa. (AP) _ When Andrew Winiarczyk's passion for books about political intrigue and the Kennedys began to overflow his three-story house, he hung a shingle out front and turned his home into a bookstore.

But when Oliver Stone's film ''JFK'' aroused decades-old questions about a possible conspiracy behind the killing of President Kennedy, the 38-year-old bookseller realized he was living in a gold mine.

His collection was a source for researchers preparing Oliver Stone's movie.

The 30,000 cache of books and other published materials on assassinations, espionage and politics is helping fill a resurgent public demand for information about the Nov. 22, 1963, assassination.

It's a demand that can pay well. A full 26-volume set of the Warren Commission report on the killing goes for $900, he said.

Winiarczyk said Tuesday his business has probably doubled in the past six months.

''We're not yet ready to retire to Miami or Dallas or New Orleans, where we can check things out firsthand,'' Winiarczyk added, referring to his wife, Linda, and their own continuing fascination with the death of John F. Kennedy.

All Winiarczyk wanted when he began the enterprise in 1982 was to clear off space on his shelves.

Winiarczyk, who holds degrees in English and Anglo-Irish studies, said the surplus of books began with his interest in the link between literature and history. Battered books picked up in bookstores on the Kennedys and espionage and the like were soon joined by copies he later found in better shape.

His collection multiplied.

''I had a number of duplicate books in my personal collection and said, 'Gee, do you think there's anyone else who might be interested in this?''' Winiarczyk said, recalling a conversation with his wife.

He made a list of some titles, and then made copies of the list, he said. And ''sooner or later, it became one of the handful of places people could turn to for books on American politics.''

Winiarczyk (pronounced win-AR-chik) calls his book business ''The Last Hurrah,'' taking the name from the title of a novel and film based on the tumultuous career of Boston Mayor James Michael Curley.

Customers range far beyond conspiracy theorists.

''They're people you see on television, they are people who live next door to you. They come in all shapes and sizes,'' he said.

Winiarczyk speculates President Kennedy probably was removed by ''renegade elements'' in the intelligence community aided by people involved in organized crime.

''If you look at it as more than just the ending of a life, but rather a coup d'etat, then we are looking at a larger issue,'' he said.