WASHINGTON -- The CIA first became aware that Aldrich H. Ames might be a Soviet mole nearly seven years ago but failed to focus on evidence pointing at the intelligence officer until last year, when officers finally searched his office, intelligence officials and members of Congress said yesterday.

Recounting the investigation that led to Mr. Ames and his wife being charged with spying for Moscow, they said the CIA's investigation of a suspected traitor in its ranks rose and fell in intensity over the years.

For instance, they said the agency took two years to question Mr. Ames after a 1989 tip from one of its own officers that Mr. Ames, who is reported to have received at least $2.7 million from Moscow, was living far beyond his means. Another year passed before the agency tried to verify Mr. Ames' response that his wife had inherited money.

The investigation finally intensified in 1992, the officials said, when Mr. Ames committed an act so careless that he betrayed himself -- traveling to Venezuela, after telling his superiors that he was going to Colombia to visit his mother-in-law.

But not until June 1993 did the CIA's internal-security officers search Mr. Ames' agency office.

Court papers released yesterday by the FBI painted Mr. Ames as a spy who grew careless in the extreme, but intelligence and congressional officials also described the CIA's long in-house search to catch him as sloppy and hapless.

" 'Unfocused' would be a kind way to put it," said Rep. Robert G. Torricelli, D-N.J., who sits on the House Intelligence Committee. "It's almost unbelievable. The system did not work."

Mr. Ames, a man who government lawyers depict as skilled enough in the arts of spying to slip off unnoticed to Vienna, Bogota and Caracas to meet his contacts, reportedly left scores of highly compromising papers and files where authorities could easily find them -- in a box in the back of a closet in his study and on a computer diskette.

Bail denied

The documents were disclosed in a three-hour hearing before U.S. Magistrate Barry R. Poretz, who ordered Mr. Ames and his wife, Rosario, held without bail.

One of the documents disclosed was a balance sheet, apparently from a contact in Moscow, that was addressed to Mr. Ames as "Dear Friend." It said that, as of May 1, 1989, Mr. Ames had received $2.7 million, far more than the $1.5 million prosecutors originally estimated that Mr. Ames had been paid over the nine years in which they say he was a mole for the Kremlin.

Federal investigator Leslie G. Wiser testified about a nine-page letter sent to Mr. Ames in the mid-1980s, which the investigator described as a "tasking list" from Moscow.

Mr. Wiser, the government's only witness, said the letter showed that Mr. Ames had furnished Moscow with the identity of an East Bloc diplomat. The agent, dubbed "GT motorboat" in the letter, had been secretly spying for the West, but Mr. Wiser testified that the diplomat vanished behind the Iron Curtain after passing secret documents to Mr. Ames.

The investigator said Mrs. Ames initially told the arresting agents that the couple had grown wealthy investing with a rich friend in Chicago. But she quickly changed her story, the investigator said, confessing that she and her husband had accepted money selling classified information to Moscow.

Eight of the 10 Soviet and Eastern European agents Mr. Ames is suspected of betraying were executed in Moscow between the time he first came under investigation and the time of his arrest, said members of Congress who have been briefed by senior officers of the FBI and CIA.

"In all, there are 10 executions tied to Ames, and most happened during these seven years he was under investigation," an intelligence official said. "These were key people involved in every component of the Soviet bureaucracy," including senior intelligence officials and a top nuclear weapons expert, he said.

The search for the mole began in 1986 after two intelligence officers at the Soviet Embassy in Washington, Valery F. Martinov and Sergei M. Motorin, who had been recruited as double agents by the FBI, were recalled to Moscow, arrested, tried and executed by firing squad.

In addition, officials said, the CIA's most important operations against the Soviet Union were failing inexplicably.

At first, the best guess was that the spy responsible was Edward Lee Howard, a CIA officer who defected to the Soviet Union in 1985, or Clayton Lonetree, a Marine guard convicted of spying from his post at the U.S. Embassy in Moscow, intelligence officials said.

But by late 1986 or early 1987, said Robert M. Gates, the former CIA director, the CIA knew it had "a continuing problem in our operations dealing with the Soviet Union that could not be explained by Edward Lee Howard or Clayton Lonetree."

Then, in 1989, the CIA was jolted when three more of its most valued Soviet double agents disappeared, intelligence officials and members of Congress said. Two were working under diplomatic cover at Soviet embassies in the United States. A third worked abroad. All were executed.

At least 200 CIA officers, including Mr. Ames, had access to the information that Mr. Martinov, Mr. Motorin and the double agents who disappeared in 1989 were secretly working for the United States. All 200 eventually fell under scrutiny.

CIA probe flounders

But from 1987 to 1991, when William H. Webster, the former head of the FBI, was director of the CIA, the investigation floundered.

Not until a joint CIA-FBI task force began working on the cases in 1991 did the investigation gain any momentum. The group narrowed its number of suspects from 200 to 20 CIA officers, again including Mr. Ames. Still, CIA officers overlooked or ignored facts that could have implicated him, intelligence officials and members of Congress said.

For example, they said, a CIA colleague voiced suspicion in late 1989 because Mr. Ames appeared to have a great deal of money for a man who made less than $70,000 a year. That year Mr. Ames paid $540,000 in cash for a home in Arlington, Va., a few miles from the agency.

Two years passed before Mr. Ames was confronted with questions about his wealth, they said. He explained that it was an inheritance from the family of his Colombian-born wife. Another year passed before the CIA investigated that claim.

In the three years that passed between the initial tip about Mr. Ames' wealth and the failed investigation in Colombia, two high-ranking Soviet agents working for the CIA, a senior counterintelligence officer and a nuclear-weapons specialist, disappeared and were executed.

In those years, Mr. Ames reportedly deposited at least $278,000 in cash into his personal banking accounts, bought a new Jaguar and ran up thousands of dollars a month in credit card charges.

Not until October 1992 did Mr. Ames blunder by traveling to Venezuela, where he met a Russian contact, according to an FBI affidavit. His travels were under surveillance.

The 1993 search of Mr. Ames' office uncovered internal documents about sensitive counterintelligence operations that had nothing to do with Mr. Ames' assignments.

Within weeks, the FBI was searching through the trash outside his house, tapping into his computer and watching his every move.