A lack of cooperation from one or more intelligence agencies led the FBI to abandon several recent criminal investigations into leaks of classified information to the press, records obtained by The New York Sun indicate.

In January 2005, a top FBI official asked the Justice Department to close three pending leak inquiries because the “victim agency” repeatedly refused to assist the probes. The FBI’s contact at the agency “has been uncooperative with the investigating field office and on numerous occasions failed to return phone calls or provide the case agent with requested documents pertinent to the investigation,” the memo said, adding that the agency “cancelled personnel interviews, security briefings and meetings at the last minute and failed to reschedule for another time.”

“None of the cases can proceed without the cooperation of the substantive unit at the victim agency, therefore the FBI considers all logical leads covered,” the FBI official wrote. Within days or weeks, the cases were closed.

The memo, which was among more than 300 pages of leak investigation files released to the Sun this week under the Freedom of Information Act, was heavily redacted by the FBI, which removed the name of the writer, the identity of the intelligence agency involved, and nearly all details about the alleged leaks.

The documents provide a rare window into the Bush administration’s effort to combat leaks of classified information that the administration has said are damaging national security in wartime. “At some point in time, it would be helpful if we can find somebody inside our government who is leaking materials, clearly against the law, that they be held to account,” the president said at a press conference last month. “Perhaps the best way to make sure people don’t leak classified documents is that there be a consequence for doing so.”

However the records suggest that reticence on the part of intelligence agencies sometimes contributes to the futility of leak probes, and that, at least when it comes to leak investigations, the much-vaunted full cooperation between the FBI and other intelligence agencies after September 11 has yet to come to fruition. “It turns out you never can find the leaker,” Mr. Bush lamented.

In an exchange of e-mails in September 2005, FBI agents handling a leak investigation codenamed “May Apple,” complained about difficulties in getting basic information about who saw classified documents key to the case. A meeting was planned with agency lawyers to discuss requests that were pending for a year. “So close it if they stonewall him tomorrow and/or we learn the distribution list is too great, right? I bet the latter will at least point us to closing even if they are totally cooperative,” one agent wrote.

A few weeks later, the head of the FBI’s leak-sleuthing section, Michael Donner, wrote to the Justice Department’s counterespionage chief, John Dion, asking to close the probe. The FBI’s Washington field office “concluded that the investigation had languished due to repeated requests for information…that have not been fulfilled in a timely manner,” Mr. Donner wrote. “Due to noncompliance from the victim agency and wide dissemination of the classified information, the FBI was unable to determine the source of the leak.” In all of the released records, the FBI deleted the name of the agency or agencies about which the investigators complained. However, a former Justice Department official said the vast majority of leak probes originate at the CIA. In the “May Apple” case, references in the files to top-secret cables and to an Office of General Counsel also point to Langley, as the government’s other main user of cables, the State Department, does not have a general counsel’s post.

A CIA spokeswoman, Michele Neff, flatly denied that her agency has resisted the FBI’s efforts to hunt down leakers. “That’s simply not the case,” she said yesterday. “Why would we not want to get to the bottom of the leaks? The Office of General Counsel works closely with the Department of Justice on investigations regarding unauthorized disclosures.”

Ms. Neff pointed to a November interview in which the current CIA director, General Michael Hayden, said recent leaking has caused serious harm to his agency’s effectiveness and to individuals. “When that takes place our ability to protect both the security and the freedom of the nation is reduced,” General Hayden told WTOP radio. “I can say as a matter of first principle that the unauthorized disclosure of classified information has actually led to the deaths of individuals.”

A Justice Department spokesman, Dean Boyd, said it is uncommon for leak investigators to encounter resistance from their counterparts in the intelligence community. “Generally, we feel we receive excellent cooperation from the intelligence agencies and other victimized agencies in leak investigations,” he said.

Ms. Neff and Mr. Boyd said they could not comment on specific cases, such as the ones where the agents reported a lack of cooperation. Mr. Dion, the Justice Department official who received the memos detailing the difficulties, and the current head of the CIA’s Office of General Counsel, John Rizzo, declined requests to be interviewed for this article.

Mr. Donner, the FBI official who oversaw some of the probes described in the memos, retired last year. In an interview yesterday, he also declined to discuss specific cases, but acknowledged some instances where agencies were not enthusiastic about helping the FBI. “They know if they do not give us more information or refuse to, the case will not push forward. They’d rather have it go away or have it dropped,” the former agent said. Many of the leak cases are initiated by the CIA, which sends the Justice Department a standard, 11-item questionnaire. Asked why an agency would refer a leak for investigation and then decline to provide necessary information, Mr. Donner said, “They have a disclosure potentially of a violation of federal law. They’re obliged to provide it or refer it to the FBI.” He said resistance may sometimes be because of legitimate concerns about further dissemination of sensitive data.

According to the records, the main reason for dropping leak investigations is that the classified information in question was so widely distributed that it is difficult to focus in on suspects. Mr. Donner said the current drive to share intelligence information made his job even harder. “I’m an old-school guy. A lot of people don’t ‘need-to-know,'” he said.

Mr. Donner, who helped crack some high-profile spy cases, such as that of Aldrich Ames, said the leak chasing was frustrating. “I wish we had better success in this area,” he said. “This stuff is a wilderness of mirrors.”

The friction apparent in the records obtained by the Sun calls into question assurances by senior government officials that law enforcement and the intelligence community are working hand-inglove to ferret out leaks. In an unusual op-ed piece published in the New York Times in February 2006, the-then director of the CIA, Porter Goss, decried illegal leaks and promised that close coordination to eradicate them was underway. The Justice Department “is committed to working with us to investigate these cases aggressively,” Mr. Goss wrote. “In addition, I have instituted measures within the agency to further safeguard the integrity of classified data.”

Mr. Goss took over in September 2004, months before the FBI’s moves to abandon the probes. However, it is unclear how much control he was able to establish over the agency. The former congressman and his staff clashed repeatedly with veteran CIA officials, some of whom quit. A top aide to Mr. Goss, Patrick Murray, who once oversaw an anti-leak task force for the Justice Department, reportedly crusaded against leaks at Langley. In May 2006, Mr. Goss abruptly resigned, offering no public reason for his departure. A former prosecutor who has accused career CIA officials of waging a leak campaign to undermine President Bush, Joseph diGenova, said yesterday that he suspected the resistance to the investigations was part of that effort. He also questioned why the leak cases were dropped.

“Stopping a leak investigation, assuming it’s a serious leak, just because the victim agency won’t cooperate is the most absurd thing I’ve ever heard in my life,” Mr. diGenova said. “A grand jury subpoena should issue….It seems to me there should be some sort of Congressional investigation of those instances.”

The disclosed records also suggest that many investigations into leaks of top-secret data are abandoned without pursuing some obvious, if intrusive, investigative techniques, such as seeking testimony or phone records from members of the press. Other components of the Justice Department have recently used those tactics in less sensitive cases, such as leaks about planned federal raids of Islamic charities and about a grand jury investigating steroid use in baseball.

“There is a stunning lack of balance in the way all these cases are approached,” Mr. diGenova said. The FBI files were released in response to a Freedom of Information Act lawsuit brought in July by this reporter. In November, a federal judge in San Francisco, citing the intense public interest in leak investigations, ordered the government to answer the requests within 30 days. The judge, Maxine Chesney, recently extended the deadline to April for some of the agencies involved.

Last month, the FBI told Judge Chesney that 22 of 94 files believed to relate to recent press leaks were missing with no indication of who had removed them.

Read the documents here.