Jurors began deliberations today in the espionage trial of retired Navy communications specialist Jerry Alfred Whitworth, the last of four Navy men charged in the Walker spy ring case to face trial.

U.S. District Judge John P. Vukasin Jr. instructed jurors that in order to convict Whitworth of espionage, they must find that, in passing highly sensitive coding information to confessed spy John Anthony Walker Jr., he intended to aid the Soviet Union or harm the United States.

The jury of seven women and five men deliberated for four hours before recessing for the weekend.

Whitworth, 46, a retired Navy senior chief radioman from Davis, Calif., has been held without bond since his arrest June 3, 1985. Dressed in a brown suit and brown tie, he sat impassively, as he has through most of the three-month trial, as Vukasin instructed the jury.

Whitworth is charged with eight counts of espionage and five counts of federal income tax violations relating to his failure to pay taxes on $332,000 he allegedly received from Walker in return for passing secrets.

The government accuses Whitworth of passing Walker copies of the Navy's daily-changing coding "key cards" and "keylists" along with design manuals for the coding machines themselves, a combination that would have permitted the Soviets to read supposedly secure Navy communications.

In closing arguments Thursday, Assistant U.S. Attorney William S. Farmer described the spy ring as "the biggest hemorrhage in the history of this country's military secrets."

Whitworth, who retired from the Navy in 1983 after 21 years, is charged with conspiring to commit espionage with John Walker from 1974 until Walker's arrest May 20, 1985.

He also is charged with six counts of committing espionage by passing Walker national defense information from the USS Constellation, the USS Niagara Falls, the Naval Telecommunications Center in Alameda, Calif., and the USS Enterprise, and one count of unlawfully obtaining national defense information from the Enterprise.

In addition, Whitworth faces four counts of filing false income tax returns for 1979 through 1982 by failing to report his espionage income, and one count of conspiracy to commit tax fraud by hiding his illicit earnings in safe deposit boxes and spending it in ways that are difficult to trace.

In closing arguments Wednesday and Thursday, defense lawyer James Larson conceded that Whitworth "received money, and a lot of it" in return for supplying classified information, and that Whitworth failed to pay income taxes on the money. Larson also acknowledged that Whitworth was the author of letters to the FBI that acknowledged participation in a Soviet spy ring.

However, he contended that Whitworth did not pass Walker any material once he realized it was destined for the Soviet Union, and did not intend to harm the U.S. when he did supply information because he thought it was going to Israel.

Assistant U.S. Attorney Leida B. Schoggen dismissed that contention as "preposterous."

Although Larson essentially conceded that Whitworth was guilty of the charges of filing false income tax returns, he said he thought it was "stretching" to find that Whitworth conspired to commit tax fraud.

The espionage conspiracy charge and the six counts of delivering national defense information carry maximum sentences of life in prison, and the charge of unlawfully obtaining national defense information carries a maximum penalty of 10 years.

The filing false income tax charges are punishable by three years in prison, and tax fraud conspiracy is punishable by five years in prison.

Vukasin told the jurors that if they do not find that Whitworth intended to help the Soviet Union or hurt the United States or had reason to believe he was doing so, they can find him guilty of the lesser offense of unauthorized disclosure of classified coding information.

John Walker, a former Navy chief warrant officer and Norfolk private detective, pleaded guilty to espionage Oct. 28 in federal court in Baltimore, and is to be sentenced to life in prison. His son, Navy Seaman Michael Lance Walker, also pleaded guilty and is to be sentenced to 25 years. John Walker's older brother, former Navy Lt. Cmdr Arthur James Walker, an engineer for a Chesapeake, Va., defense contractor, was convicted of espionage Aug. 9 in federal court in Norfolk. He was sentenced to life in prison.