An FBI agent testified yesterday that he believed accused spy Michael Lance Walker had admitted giving his father confidential documents from the USS Nimitz. The testimony came at a bail hearing for a California man accused of participating in the alleged espionage ring.

Federal magistrate Frederick J. Woelflen ordered the man, retired Navy Senior Chief Radioman Jerry Alfred Whitworth, held without bond on a charge of conspiring with John Anthony Walker Jr. since 1965 to pass secret information to the Soviet Union.

In another development today, Attorney General Edwin Meese III said there may be more arrests in the spy case.

During the course of Whitworth's hour-long hearing in San Francisco federal court, an FBI agent testified that fingerprints of three of the four suspects charged in the case were found on documents seized at the Norfolk home of John Walker, accused of being the mastermind of the alleged espionage conspiracy.

Classified documents including a manual on Navy contingency plans in the event of a war in the Middle East -- found in various searches -- also were described, as well as $22,000 in certified checks and other material that witnesses said linked Whitworth to the alleged conspiracy.

Assistant U.S. Attorney William (Buck) Farmer asked FBI agent William Smits whether Navy Seaman Michael Walker had admitted passing classified documents to his father, John Walker.

"Yes, I believe he has," replied Smits, the special agent in charge of Soviet counterintelligence at the FBI's San Francisco office.

Michael Walker's lawyer, Charles G. Bernstein, said last night he would have no comment on Smits's testimony. Walker, who is being held without bond, pleaded not guilty this week to the espionage charges.

John Walker's brother, retired Navy Lieutenant Commander Arthur James Walker, has also been arrested and charged with espionage.

Smits testified that a letter found at the Montgomery County "drop site" where John Walker allegedly left a bagful of classified documents from the Nimitz for his Soviet contact discussed another person, "F," and described family pressure on "F" from "our father."

Sources have said that "F" is John Walker's half brother, Gary Richard Walker, a third-class petty officer who was transferred last month to a Navy helicopter squadron in Norfolk. But the sources have said that Gary Walker was not implicated in the alleged espionage network.

According to Smits, the letter states that "F" "is not happy" and "may come around and good access is possible."

At a press conference in Dallas yesterday, Attorney General Meese said "there may be some more arrests" in the case. Meese said he had talked to FBI Director William H. Webster about the case and "Director Webster advised me yesterday that they're not sure yet whether there may be more arrests as they find more suspects."

Meese said the Walker case illustrates the need to cut the number of Americans -- now more than 4 million military and civilian personnel -- who are authorized to see classified documents, as well as the number of documents that are classified.

"For four years I have been saying we should have less classified information so we can really protect adequately the stuff that really ought to be secret," Meese said.

At the hearing, Smits also testified that agents who searched Whitworth's mobile home in Davis, Calif., found a 48-page manual, titled "Annex K" and labeled "confidential," outlining "communications secrets of the contingency plan for the Navy" in the event of hostilities in the Middle East.

He said that a search of John Walker's home in Norfolk had found 20 handwritten pages of documents with coded notations about high-frequency detection systems. John Walker's fingerprints were found on all the pages, Michael Walker's on one, and Whitworth's on seven, including the one page with Michael Walker's fingerprints, Smits testified.

The search of John Walker's house also revealed "an apparent payment schedule of associates of Walker," Smits said.

Alexander Seddio, a criminal investigator for the Internal Revenue Service in San Francisco, testified that he had reviewed records of 10 cashier's checks, totaling $22,000, found in a file cabinet in Whitworth's house.

He said that the checks were drawn on banks in nine locations, and that records of two indicated they had been purchased with cash. Whitworth, who has been unemployed since retiring from the Navy in October 1983, receives a pension of $1,200 monthly, Seddio said.

Farmer called the checks "icing on the cake . . . . This indicates criminal activity by someone who doesn't want to leave a paper trail."

But defense lawyer Louis Hiken disputed that inference, saying that Whitworth had amassed $20,000 in stocks and bonds by the time of his retirement.

"The amounts here do not suggest dishonesty," Hiken said.

Hiken asked that his client be released on bond, arguing that evidence indicating a link between Whitworth and John Walker did not prove that Whitworth was involved in the alleged spy scheme.

"My client has admitted from day one he has known Johnny Walker," Hiken said. "They've been friends for years. Of course there's been correspondence."

But magistrate Woelflen said that the government "has met its burden that this defendant is part of a conspipracy" to divulge secret information "which in and of itself not only constitutes a danger to this community but to the nation as a whole."

Farmer said the government intended to seek the maximum penalty of life imprisonment in the case.

Whitworth, 45, sat slouched in a chair during most of the hearing. Dressed in gray pants, plaid shirt and brown jacket, he occasionally spoke to Hiken and jotted notes on a yellow legal pad.

His wife, doctoral student Brenda Reis, did not attend the crowded hearing, but Hiken read a one-page letter from Reis saying she and her husband of nine years "have been and continue to be devoted to each other."

Interviews with friends and family members show Whitworth to be a likable, easy-going man who is proud of his Navy service and pro-American, and has visited his rural Oklahoma home town almost yearly. He was a classical music buff and gourmet cook. In 1956, his junior year at Muldrow High School, he was voted "class clown."

But FBI affidavits also shed light on Whitworth's apparently troubled personal life, and his difficulty finding work following his retirement from the Navy in 1983.

"In all honesty, I was happier in the '60s and early '70s than I've been since," he allegedly wrote in a letter addressed "Dear Johnnie" and found at the drop site. "This period (October 1983 to now) has been rough on my mental health at times."

A search of John Walker's home yielded a handwritten note, apparently by Whitworth, an FBI affidavit said. The note described career options, including, "Get a position at NCSSTK, hopefully in near future. Most likely that would be a GS-5/6 crypto operator in the Tech illegible Contract Division." Military specialists said that could be a reference to the Naval Communications Station in Stockton, Calif.

Whitworth's friends and family members in his home town of Muldrow, Okla., a small farm town near the Arkansas border, said they are shocked by the charges against him.

"Jerry was proud of his years in the Navy, and we were proud for him," said Velma Morton, an old friend whose husband taught Whitworth vocational agriculture at Muldrow High School. "If he expressed anything along the lines of politics, Jerry was anticommunist."

Whitworth for years has been a card-carrying member of the Libertarian Party, which recommends the government reduce its role in individuals' lives, she said.

Morton described Whitworth as "an all-around good guy," and added that there was never anything questionable about Whitworth's life. But she said that last year Whitworth said something to her during a visit home that puzzled her then and that she has pondered since his arrest. "He said, 'You know, you guys really don't know me.' "

His mother, Agnes Morton (no relation to Velma Morton) said her son "loved the United States. Why, he was born right here in Oklahoma . . . . He was no New York person, no Los Angeles person. He was raised in the country."

"He's well thought of by everyone, no meanness, no trouble," she said. "This is enough to drive anyone to an insane asylum."