Ronald W. Pelton was convicted today of selling Soviet KGB agents top-secret information on U.S. intelligence-gathering projects directed at the Soviet Union.

The jury in federal court here deliberated for 13 hours before returning a verdict convicting Pelton, a 44-year-old former National Security Agency employe, on one count of conspiracy, two counts of espionage and one count of disclosing classified communications intelligence to an unauthorized person. He was acquitted on one count of espionage.

Pelton received $35,000 from the Soviets for his espionage activities, which began after he left NSA in 1979.

Pelton, sitting slumped in his chair at the defense table, appeared drained but said nothing after the verdict was read. He could receive a sentence of life imprisonment on each of the espionage convictions and 10 years in prison and a $10,000 fine for disclosing classified information.

U.S. District Judge Herbert F. Murray set sentencing for July 28.

U.S. Attorney Breckinridge L. Willcox said he was "delighted" by the jury's decision and acknowledged that his office had grown concerned about the outcome of the case when a verdict was not returned quickly. Prosecutors were worried, he said, when the jury asked for further instructions to determine whether Pelton's statement to FBI agents -- the central element in the government's case -- should be thrown out.

The defense had argued that the agents violated Pelton's constitutional rights in obtaining the confession shortly before his arrest last November and that it should not have been considered as evidence against him.

The verdict, said Willcox, "clearly vindicated the FBI's handling of the case." He said the agents conducted "one of the most professionally investigated cases that I have witnessed in all my years in law enforcement."

But Fred Warren Bennett, Pelton's court-appointed attorney, said he took "severe umbrage" at the assertion that the verdict vindicated the FBI's methods and said he intends to appeal the verdict, if necessary all the way to the U.S. Supreme Court. An appeal would be based on the agents' failure to advise Pelton of his rights during the interrogation session and on threats and false promises Bennett contends the agents made to elicit incriminating statements from Pelton.

However, Bennett said his client had "an exceedingly fair trial" and that the jurors appeared to have weighed the defense arguments seriously when they began deliberations after listening to nearly seven days of testimony. He mentioned one young woman juror, who cried uncontrollably as the verdict was read and nodded her head in agreement when the judge, thanking the panel members for their work in the case, said, "I know it's hard to be a juror."

Afterward, Pelton's estranged wife Judith, who attended the trial accompanied by the couple's children and sometimes by one of Pelton's former employers, said her husband was too upset to see the family after the verdict was delivered. "I am disappointed, of course, but I can certainly see how the jury came to this decision," Judith Pelton said.

Assistant U.S. Attorney John G. Douglass, who tried the case for the government, said he believed Bennett had done a "superb job" defending Pelton. "He gave Mr. Pelton about the most effective representation that any defendant could hope to have," Douglass said.

The government, determined to get a conviction in the Pelton case, took the unusual step of airing in open court information about the United States' capability to intercept and analyze Soviet communications signals, closely guarded information that included the most sensitive national security secrets.

In an interview on the courthouse steps today, Willcox said there had been "some tension" between the Justice Department and the Department of Defense over how much information about U.S. intelligence operations to bring out in the trial. He said a "happy compromise" was reached and that he is "convinced we did not release too much information."

Willcox said Pelton, in his statement to FBI agents, revealed many details he gave to the Soviets about NSA communications intelligence projects that the prosecution was unable to present to the jury. As result, he said, the government was hampered in its prosecution. He also said that Pelton disclosed to the Soviets NSA projects and programs that were never mentioned during the trial and that were not as damaging as the disclosures discussed by the prosecution.

Willcox said the government is interested in getting a complete "damage assessment" from Pelton on the intelligence projects he compromised.

Pelton, described by witnesses as a brilliant man with an extraordinary memory for technical data, spent 14 years at the highly secret NSA as a $24,500-a-year specialist in the Soviet communications unit. He left the agency in 1979, fearing that his declaration of personal bankruptcy would jeopardize his career there.

The government has said that he began his espionage activities six months later, walking into the Soviet Embassy in Washington and disclosing the secret location of U.S. equipment used to intercept military communications on a particular Soviet communications link. With information about that equipment and its operation, referred to in court as Project A, the Soviets would have been able to take countermeasures, the prosecution argued.

Bennett said one element of his appeal of the verdict would be Judge Murray's refusal to allow an NSA witness to be questioned on an "incident" that occurred in the late 1970s. The defense argued that the "incident" led Pelton to believe that the Soviets knew about Project A even before he told them about it.

The Washington Post has reported that Project A was a submarine operation to intercept Soviet communications. Pelton, using a map, told FBI agents the operation was in the Sea of Okhotsk between the Kamchatka Peninsula and the eastern Soviet mainland. The "incident," according to a knowledgeable source, was a collision of a U.S. submarine and one from the Soviet fleet.

Pelton also was accused of participating in two lengthy debriefing sessions at the Soviet ambassador's residence in Vienna, disclosing to the Soviets four other top-secret NSA projects and information contained in what the government termed "an encyclopedia" of what the United States knows about Soviet signals intelligence. That document, the Signal Parameters File, was written by Pelton in 1978, when he held a middle-management level job at NSA.