Jury selection began today in the trial of retired Navy communications specialist Jerry Alfred Whitworth as a federal judge denied a defense effort to have eight espionage charges against him tried separately from five income tax counts.

Defense lawyers had said that Whitworth, the last of four men charged in the Walker spy ring case to face trial, wishes to testify about the espionage charges but not the tax matters. Refusing to separate the charges, they argued, would force Whitworth to choose between his right to testify in his defense on the espionage charges and his constitutional right against self-incrimination on the tax charges.

U.S. District Court Judge John P. Vukasin Jr. said, however, that he saw no need to split the trial for that reason. He said prosecutors would still be able to question Whitworth about whether he had made false statements on his tax returns even if the tax counts were severed.

"The probability" of infringing on Whitworth's rights, he said, "does not exist."

Whitworth's lawyers did not explain in open court his reasons for not wanting to testify about the tax charges, but defense attorney James Larson suggested that his client believes he has a better defense to the espionage case.

"If the truth is that he had no defense in respect to the tax charges . . . and he takes the stand in a joint trial and admits his guilt on the tax charges, then that will have a . . . spillover effect on the espionage charges," Larson said.

In addition, he said, prosecutors in a combined espionage and tax case could ask Whitworth -- if he admitted failing to report his full income -- where the money came from, "which would deal directly with the espionage charges."

Larson said he did not know whether Whitworth would testify in light of the judge's ruling.

Whitworth, who retired from the Navy as a senior radioman in 1983, is charged with passing convicted spy John Anthony Walker Jr. highly sensitive Navy secrets in an espionage conspiracy that allegedly started in 1974 and lasted until Walker's arrest last May 20. He is also charged with tax fraud and failing to pay federal income taxes on $332,000 he allegedly received from Walker.

The first juror to be questioned was Catherine Allan, a computer graphics artist who said she had heard about the Whitworth case only once, in a brief reference on television.

"I really didn't pay any attention to it," she said. "I just remember Mr. Whitworth's name, the Walkers' and espionage."

He excused another juror who said she had worked for four years for the CIA and who added that it would be difficult for her to convict anyone of a crime.