A federal judge in Baltimore ruled yesterday that prosecutors can use statements that Ronald W. Pelton's made to the FBI before his arrest as evidence in his espionage trial, which is expected to begin early next week.

While U.S. District Judge Herbert F. Murray said he was "somewhat troubled" and puzzled by the behavior of the FBI agents who questioned Pelton, he rejected defense arguments that the agents misled Pelton and failed to inform him of his rights when they should have.

Pelton's statements during five hours of interviews in late November are the crux of the government's case against the 44-year-old former communications specialist for the National Security Agency. Pelton is accused of selling Soviet agents extremely sensitive information about U.S. intelligence-gathering systems directed at the Soviet Union.

Fred Warren Bennett, Pelton's attorney, said he was disappointed by the judge's ruling but that he would to challenge the agents' behavior, as well as the constitutionality of evidence taken from wiretaps, during Pelton's trial.

He said "there are no discussions" of a plea bargain, indicating that prosecutors would never agree to a prison term much less than the life sentence Pelton faces if convicted on any one of five charges.

"You saw what Arthur Walker got in Norfolk, and what John Walker is going to get," Bennett said. "Even with cooperation, we don't think it's a significant enough inducement in this case to discuss a plea."

Bennett had argued at hearings that FBI agents should have told Pelton of his rights to be silent and to have an attorney because Pelton was essentially "in custody" during the interviews at an Annapolis hotel. But Murray noted that the agents let Pelton leave the hotel for lunch and that Pelton returned for the interview at night.

Murray also said that Pelton was capable of deciding whether to talk, despite his testimony that he had drunk two glasses of Grand Marnier and a half of a fifth of vodka and injected four milligrams of the narcotic Dilaudid before the night interview.

In his ruling, the judge said that in general Pelton "demonstrated a great deal of knowledge of the seriousness of the interrogation and certainly had a 'layman's' awareness of important legal concepts.

"The defendant is an intelligent person with a great deal of experience, which would make him an unlikely personality to be coerced into an involuntary confession," the opinion stated.

Murray found "some merit" in Pelton's argument that the agents implied that the government would use him as a counterintelligence agent instead of prosecuting him if he cooperated.

"For example, the court finds it difficult to understand why the agents expressed concern to Pelton about his drug purchases and use," as if they worried whether he would be reliable as an agent, the opinion said.

The judge also said he was "somewhat troubled" that the agents told Pelton they could not discuss national security matters in front of a lawyer unless the lawyer had proper clearance.

"Although technically they did not deny the defendant an attorney, the court believes it would have been more in keeping with the spirit" of the law "for the agents to have explained more carefully what they would and would not discuss in front of an attorney and the implications for the defendant," the opinion said.

But the judge ruled that the "totality of circumstances" showed that Pelton spoke voluntarily.