ATLANTA » In February 2007, Alberto R. Gonzales, the attorney general under President George W. Bush, warned those who murdered blacks with impunity during the civil rights era: "You have not gotten away with anything. We are still on your trail."

He noted that time was short. The window of opportunity to solve racially motivated crimes more than 40 years old was closing. Families of the victims had waited decades for resolution, while suspects and witnesses had died.

More than three years later, they are still waiting.

There have been no federal indictments since Gonzales’ announcement, which heralded the Civil Rights-Era Cold Case Initiative. Very little of the millions of dollars approved by Congress to finance the initiative has materialized. Although 40-year-old murder cases are incredibly difficult to solve, no Federal Bureau of Investigation field agents are assigned to pursue the cases full time.

Those who hoped for an all-out law enforcement effort to beat the clock, akin to the search for the Unabomber, have been sorely disappointed. Instead, witnesses say, the FBI has taken months or years to approach them.

President Barack Obama’s attorney general, Eric H. Holder Jr., has promoted his department’s handling of these cases, pointing out that 56 of 109 have been closed, with many more on the brink. The department has taken the unusual step of writing letters to the families of victims, detailing the findings and explaining why the case cannot be pursued further — in many cases, because the suspect is dead.

But critics say the numbers are misleading, because instead of aggressively investigating the dozen or so cases that might still yield a viable prosecution, the department has taken the easier route of closing the ones that were long shots to begin with.

"If this whole effort goes through and there’s no evidence of an aggressive manhunt and it results in no prosecutions, then there will not be a credible acceptance of the results by the American people," said Alvin Sykes, the president of the Emmett Till Justice Campaign in Chicago and an instrumental force in the passage of the Emmett Till Unsolved Civil Rights Crime Act in 2008.

Federal officials bristled at the criticism, saying that it is premature and that they have an obligation to review every case and bring "closure" to families.

"We have always known that locating the subjects, witnesses and evidence for 40-year-old murder cases was going to be challenging, and that many of these matters would not be prosecutable," said Xochitl Hinojosa, a spokeswoman for the Justice Department.

But families yearn for action. Over the years, relatives of Louis Allen, a civil rights worker who was ambushed at his front gate in Liberty, Miss., in 1964, have met with countless officials and offered a $20,000 reward.

"Everybody put me on the back burner for years and years," said Allen’s son, Henry C. Allen, 65.

He had hoped the cold case initiative would change things but said the response has been slow. He said the legwork had been done.

"Here’s the people you can contact, here’s their phone number, here’s their address," he said. "I don’t have the authority to go knock on their door, but you do — and it still don’t get done."

Special Agent Cynthia Deitle, chief of the FBI’s civil rights division, said that agents were not permitted to share the progress of continuing investigations with families or the public. Witnesses, she said, might not always be forthcoming about having cooperated with the FBI. The Allen case remains open.

The Till bill authorized up to $13.5 million a year to solve racially motivated murders before 1970, but in fiscal year 2009 no money was allocated. In fiscal year 2010, the Justice Department received $1.6 million for civil rights cold cases. The FBI received an $8 million increase for its civil rights division, which handles human trafficking, hate crimes, present-day civil rights violations and cold cases, a spokesman said.Officials have repeatedly insisted that lack of money was not an obstacle.

"There’s never been a resource issue whether it was people or money on our end," Deitle said.

Agents have pored over thousands of documents, interviewed hundreds of people and hiked into the woods with Global Positioning Systems to determine whether a killing fell under federal jurisdiction,she said.

More than 20 civil rights cases have been successfully prosecuted since 1994, including the 2005 conviction of Edgar Ray Killen, 85, one of the Klansmen responsible for the 1964 deaths of three civil rights workers, James Chaney, Andrew Goodman and Michael Schwerner.

Those prosecutions were driven by the persistence of surviving family members and the work of journalists and documentary filmmakers.

The cold case initiative was supposed to put the Justice Department in the lead. But reporters like Jerry Mitchell of The Clarion-Ledger in Jackson, Miss., one of the foremost experts on civil rights-era cases, say investigators are still lagging behind and sometimes are even failing to follow up on leads that journalists, usually working from leaked copies of the FBI’s own aging files, turn up.

After Killen was convicted, Mitchell continued to investigate.

In 2007, after combing through thousands of pages of leaked FBI files, he published interviews with two women who, hours before the killings, were in the car of a deputy sheriff for an unrelated reason. The women heard the deputy discuss the three civil rights workers with Billy Wayne Posey, a Klansman.

But the FBI showed no sign that it, too, was pursuing an investigation until the summer of 2009, Mitchell said. It was only last fall, after Posey died, that the FBI contacted the two women, one of them, Linda Johnson, said in a telephone interview.

Stanley Nelson, the editor of The Concordia Sentinel, a weekly in Ferriday, La., has been cranking out stories on a cluster of killings in that area and were connected to the Silver Dollar Group, a Klan organization that terrorized the area with impunity in the 1960s. He has worked with the Syracuse University College of Law’s Cold Case Justice Initiative, where students have gone through thousands of FBI documents, even finding files on a missing black hotel porter, Joseph Edwards, that a federal prosecutor had said the bureau did not have.

In another case, that of Frank Morris, a black cobbler who died from burns after his shop was set on fire, it was Nelson who found and interviewed a witness, a black teenager who worked at the store. At the time, his mother forbade him to speak to law enforcement officers.

"When we started the Frank Morris case," said Janis McDonald, the co-director of the Syracuse project, "The FBI said, ‘You know, just about everybody is dead."’

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