Cmdr. Donal M. Billig revealed to Navy recruiters before he was commissioned that his surgical competence had been questioned by a New Jersey hospital, but Bethesda Naval Hospital officials found out only when Billig's ex-wife threatened to expose his past a year later, according to arguments made during two separate courts-martial yesterday.

That chronology became apparent during the courts-martial of Billig and Cmdr. Reginald E. Newman, charged with lying about his role in the recruitment of the doctor in 1982.

Billig, the former head of cardiothoracic surgery at Bethesda, is charged with involuntary manslaughter of five patients there. He pleaded not guilty to the charges yesterday and opted for a jury trial rather than trial by military judge.

The case against Billig moved closer to trial as Capt. Philip Roberts, the judge, overruled strong objections from the doctor's defense attorney and agreed that the prosecution could bring preserved human hearts into the courtroom for jurors to examine.

Roberts said the hearts, which prosecutors said would be examined with the use of gloves, would help the jurors understand how the organ works. The specimens would not be allowed if, when they are brought into the courtroom, Roberts found them to be "tasteless," he added.

That decision came minutes before the prosecution revealed that Bethesda Naval Hospital officials were first informed in 1983 of previous surgical problems facing Billig, only when his ex-wife said she would tell officials about his practice at Monmouth Medical Center in New Jersey. In 1980, a review panel of doctors there said the surgeon lacked good judgment, proper motivation and honesty. Billig later resigned from the hospital and surrendered his New Jersey license.

"His experience at Monmouth only surfaced when his former wife threatened him with blackmail," Lt. Cmdr. Joseph VanWinkle, a prosecutor, said at the pretrial hearing yesterday. VanWinkle and Navy spokesmen later refused to elaborate.

Billig's defense attorney, Lt. Stephen Baker, later said that Billig, who had been divorced from his first wife, Marilyn, was threatened by her after he had not met some alimony payments. Bethesda Naval Hospital then was told and inquired into the problems at Monmouth, he said.

It was unclear yesterday whether Billig's ex-wife informed Bethesda officials or the doctor did after the threat.

As Billig's attorneys prepared for jury selection at the Navy Yard, the first witnesses testified in Newman's trial, held at Bolling Air Force Base. Former Pittsburgh recruiter Lt. Cmdr. Jerry D. Penn, who also is charged with lying about his part in recruiting Billig in 1982, said Billig was open about his troubles at Monmouth.

Moreover, Penn testified, Billig wrote "yes" when asked on a Navy questionnaire if there was anything in his past Navy officials should be aware of. But that answer was later changed by someone in the Pittsburgh recruiting office at the instruction of Newman, Penn's superior based in Washington, Penn said.

"I understood that I was to change [the answer] from a yes to a no," Penn testified. "I don't remember if I changed it, but it was changed."

Newman told Penn the Monmouth information "was not pertinent," Penn said. "He agreed with my opinion [that the Monmouth controversy] was a matter of some professional jealousy on the part of his accusers," Penn said.

Newman is charged, among other things, with lying about whether he supplied information about Billig's record to officials responsible for reviewing the professional qualifications of applicants. Prosecutor Lt. Elizabeth Dean, in her opening statement, said Newman also lied when he told officials that Monmouth had issued a letter indicating Billig had left his post there in good standing.

Dean said yesterday the Navy may drop some of the charges against Penn, in light of new evidence and his testimony. Penn has been given immunity for his statements in the Newman case.

Newman's defense attorney, Lt. Cmdr. Irving Warden, in opening arguments, said he would question the credibility of some prosecution witnesses.