The film Ruby' examines the mystery of the Texas Jew who shot Kennedy's assassin.

The night before Jack Ruby gunned down Lee Harvey Oswald - just two days after President Kennedy was shot dead - he spent the night in a Dallas synagogue weighing his conscience.

"Ruby was very apprehensive about what his actions would lead to for the Jewish people," says Stephen Davis, the 41-year-old screenwriter responsible for "Ruby," an independent feature film about the tawdry life of the Jewish nightclub owner and small-time hood whose murder of Oswald made him a national figure.

Based on "Love Field," a play by Davis staged in London seven years ago, "Ruby" was made for just under $ 10 million - a quarter of what Oliver Stone lavished on "JFK." Due to make its U.S. premiere on March 27, "Ruby" stars Italian-American actor Danny ("Moonstruck" and "Do The Right Thing") Aiello in the title role and Sherilyn Fenn (Audrey in the cult TV-series "Twin Peaks") as a composite fictional bar-girl called Candy Cane.

Jack Ruby was a low-level Dallas mob enforcer and sometime FBI informer who owned a Dallas nightclub called the Carousel. For Davis, Ruby was also the quintessential ethnic American, fiercely proud of his identity and extremely prickly about perceived anti-Semitic slurs.

"Ruby's Jewishness was obviously intrinsic to his character," says Davis. "He was a lapsed Jew who was still proud and asssertive of his Jewish identity."

Davis notes that toward the end of his life in a Texas jail cell, juggling two death sentences one imposed by a Texas court and another by the cancer which eventually took his life in 1967 Ruby began raving about a worldwide conspiracy to subject the Jews to mass torture.

By this time, he believes, Ruby "became clinically quite paranoid. Remember, he had been through an ordeal. He was in captivity and had been sentenced to death. The fact that his stability gave way was not in the least bit surprising."

The screenwriter himself is a second-generation British Jew of East European stock. "The Dissolution of Marcus Fleishman," a radio play broadcast by the BBC in 1975, when was 24, and later televised, was his debut as a playwright.

Its theme: A man dies in the Holocaust, and is reincarnated as a laboratory ape subjected to genetic experiments by his own son.

"Having been born in 1950," he recounts, "I found it shocking and sobering that only five years before that, my parents' generation were being herded into the death camps. It's not as if that were another planet. English Jews escaped by a whisker."

Yet in bringing Ruby to the screen, Davis felt impelled to downplay his protagonist's Jewishness to a fondness for kosher pickles and a burly defensiveness about his origins; his delusions about a plot against world Jewry were deliberately left out of the script, and Ruby's visit to the Dallas synagogue, although shot, ended up on the cutting room floor. "His Jewishness was obviously a red herring to his actions," says Davis."I don't think the ultimate analysis of what happened on November 22, 1963 will ever turn up a Jewish card. Ruby's Jewishness was merely one thin thread in the tapestry."

At various stages during the Warren Commision investigation, Ruby hinted that he knew far more about the Kennedy assassination than anyone, including the commission (which ultimately found that Oswald had acted alone). This has served as the springboard for Davis's script.

"Of all the chess-player characters the Kennedy assassination research throws up," he says, "the tortured and apocalyptic remarks Ruby made in captivity chimed with my sense of the assassination as a mystery, as a deep complexity. I discovered in him a vivid, dramatic, small-time character who'd stumbled into something well over his head."

Discounting the "unified conspiracy theory" which Oliver Stone puts forth in "JFK," involving the entire American military-industrial complex in a virtual coup d'etat, Davis puts forth in "Ruby" the idea that the president was assassinated as the result of an out-of-control collusion between the CIA and the Mafia.

"I take a more plausible view of events than some people think Stone does," says Davis. "I find it difficult, if not impossible, to digest the idea of military coup.

"I think there is a danger of replacing the unbelievable mythology of the Warren Commission with a new kind about a military coup. I find it inconceivable that the American military establishment could carry out this stunning coup in broad daylight and cover it up for 27 years."