Joseph A. Cafasso knows people - retired admirals, generals, government officials. More to the point, he has said, he knows his way around the netherworld of counterintelligence through contacts he built during a sterling career as a lieutenant colonel in the Special Forces.

The Fox News Channel thought it had found an asset when it hired the gruff, barrel-chested former military man as a consultant to help in its coverage of the fighting in Afghanistan. He claimed to have won the Silver Star for bravery, served in Vietnam and was part of the secret, failed mission to rescue hostages in Iran in 1980.

For more than four months, Mr. Cafasso assisted and shared tips with reporters, producers and on-air consultants. Then on March 11, he abruptly left Fox amid complaints that he had overstepped his bounds and had become an annoyance. Soon afterward, Fox News, and many associates of Mr. Cafasso, learned that his office style may have been the least of his problems. The real story, many people say, was that he was not who he said he was.

He released a statement on Sunday in which he said he was the victim of a "gossip campaign" by "self-centered individuals with their own political agendas."

People at Fox News had taken his credentials at face value. So had the presidential campaign of Patrick J. Buchanan, for which he was an organizer; WABC radio in New York; and several representatives, military officials and activists to whom he had sold himself for years. But records indicate that his total military experience was 44 days of boot camp at Fort Dix, N.J., in May and June 1976, and his honorable discharge as a private, first class.

Mr. Cafasso had promised to appear at The New York Times to provide documents contradicting records that he only served in boot camp but never appeared. Military officials said they had no record of anyone named Joseph Cafasso retiring as an lieutenant colonel.

Mr. Cafasso, it appears, has used his story of battlefield glories to make friends, find work, and perhaps most importantly, find acceptance among people who walk the fringes of Washington's power corridors, networking his way through a community of retired military officers to arrive at Fox News.

Fox News would not be the first news organization to be deceived. The New York Times in March reported the account of a former Russian army officer who said he fled the fighting in Chechnya in 1999 to escape pressure to kill civilians. On Saturday, The Times quoted Russian officials and acquaintances as saying he was not serving in the army at the time.

Fox News executives acknowledged that they now think that Mr. Cafasso was not who he said he was. But they said that the information he gathered never led to any known mistakes and that he had a network of military sources - built, apparently, on the strength of his stories.

Whatever the case, Mr. Cafasso seemed to have contacts where network reporters had few, they said, and he worked long hours, often helping the network penetrate the secrecy that shrouds the Pentagon.

Mr. Cafasso was introduced to the network shortly after the start of the military campaign in Afghanistan by retired generals whom he accompanied to Fox's offices in Washington, where they appeared as commentators. Executives said Mr. Cafasso seemed to be a consultant, briefing the generals on developments in Afghanistan. As he spent more time at Fox deciphering military movements, the executives eventually felt compelled to hire him as a consultant for $200 a week.

One senior Fox executive said Mr. Cafasso was so convincing and seemed to have such respected patrons at the Pentagon that there was no reason to question him. "He was so confident," the executive said. "The sheer brazeness of it is just remarkable."

The executive added that Mr. Cafasso was hired because of his contacts, not necessarily his military background. "Joe was just plugged in everywhere," the executive said. "He appeared to be able to call almost any military base and have a friend there."

Executives at Fox said Mr. Cafasso often worked late hours chasing leads through his sources, setting up interviews with military officials and offering guidance to producers trying to understand the foggy Afghan battlefield. He developed skills on the network's graphics computer - used for on-screen maps - and prepared briefing packages with news clippings for commentators.

"He knew more about the military and the Pentagon than most reporters we deal with," said a military officer at the Defense Department who was surprised to hear that he was not a decorated veteran.

He also had a good sense of military spin, counseling the Fox staff to be cautious about Pentagon claims in December that troops had Osama Bin Laden cornered. He quoted sources as telling him that Mr. Bin Laden could easily escape through the mountains, which has been raised as one possibility of what may have happened.

Fox executives conceded that one piece of advice from Mr. Cafasso could have saved the network considerable embarrassment, if it had acted on it. In February, Fox and ABC erroneously reported that the body of the Wall Street Journal reporter Daniel Pearl had been found, based largely on information from a police official in Karachi, Pakistan.

Mr. Cafasso had, correctly, told Fox that his contacts were telling him the report was bogus. Yet Mr. Cafasso's information could sometimes be flawed. He would often make mistakes on the names of people and places, people at Fox said. Once Mr. Cafasso alerted the staff that black helicopters were descending on the State Department, apparently to battle a terrorist threat there. Fox staff in the building ran outside to find blue sky, a person close to the incident said.

Either way, as policy, Fox executives said, producers and correspondents were required to verify information offered by Mr. Cafasso.

Some doubted his credentials. In November, an executive asked a private security consulting and training firm to look into Mr. Cafasso's service record. The firm, called the Spartan Group and made up of Special Forces veterans, concluded that Mr. Cafasso was lying about the hostage mission in Iran and said it could find no service record for him.

"He was a fraud," said Tim Buckholz, director of the Spartan Group's corporate security arm, after Mr. Cafasso left Fox. Discussing Mr. Cafasso's claims that he participated in the rescue attempt, Mr. Buckholz said he talked to several individuals involved. "That was a very closed mission," he said. "And nobody knew a Cafasso. We told Fox that."

Fox said a researcher in New York who had clashed with Mr. Cafasso had asked the Spartan Group to look into his record, independently. Only after his departure did executives learn of the inquiry and its results, which did not conclusively disprove his story.

Still, after several months, Mr. Cafasso began to wear on the nerves of some Fox staff members. For one thing, he did not shy away from telling them they were off-base.

The Washington bureau chief for Fox News, Kim Hume, finally decided to let him go, people at Fox said, and he decided he was ready to leave. In an e-mail message to the staff, Ms. Hume wrote that Fox's "military and counterterrorism consultant," Mr. Cafasso, "made crucial contributions to our coverage of the war on terror" and helped take "Fox's war coverage to the next level."

Mr. Cafasso, reached on his cellphone, said in a brief interview, "I left because I had enough; I don't like the press." Yet he sent the staff a gracious note. "I opted to depart without fanfare because this is the way I am," he wrote. "One day there, the next not."

That, too, is how former associates describe Mr. Cafasso. Before his arrival at Fox, Mr. Cafasso spent years flitting in and out of military and political circles, impressing people with his stories and disappearing when people began to doubt him.

Born in 1956, he graduated from Carteret High School in Carteret, N.J., military records show. He is described by people who know him as an imposing figure with graying hair, tobacco-stained teeth and a gruff voice. He is considered a gifted storyteller whose tales can keep people riveted for hours.

It appears Mr. Cafasso was introduced to many of the retired generals with whom he built relationships by Rear Adm. Clarence A. Hill Jr., former commanding officer of the the aircraft carrier Independence and once a colleague of Rear Adm. John M. Poindexter, a former national security adviser.

Mr. Cafasso first met Mr. Hill at a conference in 1997 held by the conservative media group Accuracy in Media, where Admiral Hill spoke about his theory that TWA Flight 800 was shot down by a missile when it crashed off Long Island in July 1996.

"He made enough of an acquaintanceship with me at the time to arrange a later meeting, and he had information about TWA 800," Mr. Hill said.

Mr. Cafasso was so enthusiastic about the missile theory that Mr. Hill introduced him to like-minded military men, like Adm. Thomas H. Moorer, former chairman of the Joint Chiefs of Staff, and William S. Donaldson 3rd, a retired commander in the Navy.

Mr. Cafasso's collaboration with Mr. Donaldson on TWA the crash ended abruptly when Mr. Donaldson asked to see his partner's service records and Mr. Cafasso told him they were sealed, Mr. Hill said. When the records were not provided, Mr. Hill said, Mr. Donaldson, who died last August, ended the collaboration.

Mr. Hill said he regretted introducing Mr. Cafasso to a group of veterans and American and Serbian activists concerned about the humanitarian conditions in Yugoslavia after the NATO military campaign there. Mr. Cafasso helped the group lobby for aid to the wartorn region, people involved said.

"He's overwhelmingly convincing," said David Vuich, a member of the Serbian group. "He walks sometimes with a cane and made reference to it being something that he had experienced in Vietnam."

Mr. Cafasso finally had a falling out with some in the advocacy group in late 1999 when they thought he was trying to take over its leadership, several members said.

Not long afterward Mr. Cafasso began to work with the presidential campaign of Patrick J. Buchanan, helping it collect petitions in Texas and then in Oklahoma and Georgia.

By last summer, he was working, for free, for the crisis-obsessed, politically wired program of Paul Alexander and John Batchelor at WABC Radio in New York. Phil Boyce, the programming director there, said Mr. Cafasso approached the program claiming to have leads on stories but quickly began to overstep his bounds. He was dismissed within a few weeks. "He began to introduce himself as an executive producer and began to tell my employees what to do," Mr. Boyce said. "Once I found out, I put a stop to it."

Mr. Vuich of the advocacy group said he was surprised when Mr. Cafasso appeared at a reception at the Yugoslavian embassy in Washington as a representative for Fox News in early November. "How he had managed to wiggle his way into Fox was beyond me," Mr. Vuich said.

At that point Mr. Vuich and two others from the advocacy group, John Saylor and Ben Works, decided to check Mr. Cafasso's military record, the men said in interviews. Mr. Works received Mr. Cafasso's record from the national personnel records bureau in St. Louis and gave it to people at Fox and other Cafasso associates. But Mr. Cafasso had just left the network.

Mr. Cafasso has recently been seen on Capitol Hill, representing himself as a consultant for Midwest security company.

On Friday he said he was doing crucial secret work, adding that he could not cooperate because of "national security." On Saturday, he offered an explanation of his work but would not do so for publication.

On Sunday, he sent an e-mail message: "This is nothing more than political assassination by a group of self-centered individuals with their own political agendas, who enjoy half-truths, gossip and hiding behind the press for their own self-worth. I will not be tried by the press and small-minded individuals such as these that have no clue to what is real or not."

Hanoi Jane Fonda