NEW YORK » The death of Malcolm X, shot dead at the Audubon Ballroom in Harlem in 1965, never inflamed the public imagination in the same way the assassinations of John F. Kennedy and Martin Luther King Jr. did. But scholars have long believed that a bungled investigation resulted in the imprisonment of the innocent and allowed some of those responsible to go free. Over the decades, efforts to reopen the case have failed.

Now a best-selling biography has helped to renew calls for a full investigation. But this time they may well gain traction because the legal environment has changed: Prosecutors in the South have demonstrated that it is possible to pursue and win cases that are decades old, and, as a byproduct, they have made the failures of the police in the civil rights era abundantly clear.

At the same time, news has emerged that the man long suspected of having fired the shot that killed Malcolm X but who was never arrested is living in Newark, N.J., under a different name.

"Time is running out; these guys are very old," said Abdur-Rahman Muhammad, a graduate student at Howard University who first published the identity of the Newark man on his blog and was a source for the biography’s author, Manning Marable. "I wanted justice to be done, and I knew that Marable wanted justice to be done."

Marable, a historian at Columbia University, died days before the publication of the book, "Malcolm X: A Life of Reinvention."

The effort to reopen the case has attracted the attention of the nation’s most persistent advocate of civil rights-era justice, Alvin Sykes of Kansas City, Mo. Sykes was instrumental in the reopening of the investigation into the killing of Emmett Till in Mississippi in 1955 and in persuading Congress to allocate millions of dollars to the investigation of civil rights cold cases. Sykes has asked both the Justice Department and, this week, the New York state attorney general "to conduct the most comprehensive and credible search by the government for the truth concerning Malcolm X’s assassination."

The cause has made for strange bedfellows: Ilyasah Shabazz, one of Malcolm X’s six daughters, is supporting the call to reopen the case despite her objections to the biography, which paints a bleak picture of her parents’ marriage. Leith Mullings, the author’s widow, is also asking for an investigation.

But it will be an uphill battle, partly because three men were convicted at the time, meaning the case is potentially a hybrid of two separate areas of criminal law: a civil rights cold case and a wrongful conviction.

Malcolm X, who became a patron saint of the black power movement and, long after his death, a U.S. icon, knew his life was in danger when he took the stage at the Audubon Ballroom on Feb. 21, 1965. He had broken with the Nation of Islam, which had branded him an enemy and a traitor. A week earlier, his house had been firebombed. As he began to speak, a disturbance broke out in the audience, a smoke bomb went off, and gunmen opened fire.

Thomas Hagan, a 22-year-old member of the Nation of Islam from New Jersey, was arrested at the ballroom that day. The police investigated the crime scene for four hours before the blood was mopped up and a planned dance began.

The police later picked up two more Nation of Islam members: Muhammad Abdul Aziz, then known as Norman 3X Butler; and Kahlil Islam, then Thomas 15X Johnson. In his book, Marable says that the Nation of Islam would not have used men from Malcolm X’s own mosque to carry out the killing and that the assassins were from New Jersey. Hagan confessed but always maintained that the other two men were not involved. At the trial, he testified there were other conspirators but refused to name them. All three men were convicted, but the question of how high the conspiracy went in the Nation of Islam hierarchy — who, in fact, ordered the killing — was never answered.

David Garrow, a historian and a King biographer, obtained and reviewed the Federal Bureau of Investigation files on Malcolm X in the 1990s. He said it was probable that reams of wiretaps of the Nation of Islam had never been combed for clues. In 1980, the bureau said it had never investigated the assassination.

In the late 1970s, Hagan, also known as Talmadge X Hayer, finally identified his accomplices in an affidavit as part of an unsuccessful effort to free Butler and Johnson (all three men have since been paroled).

One of the names he gave was Willie X, whom William Kunstler, the civil rights lawyer who represented Johnson and Butler, determined was William Bradley. The others are dead or presumed dead. Marable wrote that Bradley, using a sawed-off shotgun, fired the fatal shot.

Bradley, an ex-convict now in his early 70s, is living in Newark under the name Al-Mustafa Shabazz. (Police records list both names for him.) He is married to Carolyn Kelley Shabazz, described by The Star-Ledger of Newark as a community leader and the owner of a boxing gym who gives away turkeys at Thanksgiving.

Al-Mustafa Shabazz served time for conspiracy, drug dealing and making "terroristic threats," according to records at the New Jersey Corrections Department, and was released in 1998. Through his lawyer, J. Edward Waller, Shabazz has denied any involvement in the assassination.

Sykes, who cautions that he has yet to personally see proof linking the name Willie X to William Bradley, would like to see state and federal officials conduct a joint investigation, but the Manhattan district attorney has jurisdiction over the case.

Sykes said he would rather that other agencies were involved, because the Manhattan district attorney’s office investigated the killing in the first place.

But there are limitations on other agencies’ ability to investigate. For one, it is not clear if the killing could be considered a civil rights crime because both the perpetrators and the victims are black.

Garrow said the definition of a civil rights crime should not be too narrow.

"When a major civil rights leader is assassinated, I’d like the civil rights division to be interested, regardless of the color of the gunman," he said, referring to the federal unit.

Some experts say the Justice Department’s participation is crucial because the FBI and the New York Police Department had Malcolm X under surveillance at the time of his death, raising questions about whether law enforcement officials had knowledge beforehand of the assassination plot.

Still, the Justice Department may not have any jurisdiction, and the department has only occasionally investigated without it — in 1998, for example, then-Attorney General Janet Reno ordered a limited review of the King assassination after pressure from the family and the public.

The New York attorney general may investigate only if asked by the Manhattan district attorney or the governor. But cases that are decades old are not easy to solve, said Doug Jones, a former U.S. attorney in Birmingham, Ala., who helped prosecute the 16th Street Church bombing.

"A lot of people think witnesses come forward after so many years have passed," he said, "but they don’t."