A CIA official supervising Aldrich H. Ames, the convicted spy, warned more than three years before Ames was arrested that he was a potential turncoat with an inexplicable fortune, according to a CIA memorandum made public Monday.

The December 1990 memo said that Ames, then one among more than 20 suspects in the on-again, off-again hunt for a traitor within the agency, had in recent months spent more than $600,000 from an unknown source.In the mid-1980s, as a counterintelligence officer, Ames "had access to a number of operations that were later compromised" and disclosed to the Soviet Union, the memo said.

But the CIA did not act quickly to share the incriminating financial data with the FBI, which is responsible for catching spies within the United States, the chairman of the Senate intelligence committee said.

Thirty months passed before the start of a formal criminal investigation of Ames, who was arrested in February and pleaded guilty in April to being a mole for Moscow inside the CIA for nearly a decade.

It has become clear that "appropriate resources were not dedicated promptly in the Ames case," as CIA Director R. James Woolsey said two weeks ago. Infighting and lack of communication between the CIA and the FBI hampered the investigation, according to a variety of federal officials, including Sen. Dennis DeConcini, D-Ariz., the head of the Senate intelligence committee.

But the memo, declassified last week and released Monday by DeConcini, who has sharply criticized the CIA's performance in the Ames case, was the first indication that the CIA knew as early as 1990 that Ames was spending huge sums of money in ways that could not be explained by his salary, which never exceeded $70,000 a year.

The memo "speaks for itself," said DeConcini. "They actually had the information way back in 1989, they finally reduced it to writing in December 1990 and they really didn't do anything with it, which is unbelievable in my opinion."

The memorandum was written by a senior officer at the CIA's counterintelligence center, where Ames worked at the time, and was sent to a senior officer at the CIA's office of security.

The names of these two officials were deleted from the memorandum before it was made public Monday and an agency spokesman would not identify them.

The CIA has strongly disputed DeConcini's assertion that there was discord within the joint task force it had formed with the FBI to pursue the investigation in late April or early May 1991.