A U.S. court jury today convicted Walter Weikers, a 67-year-old suburban Baltimore furniture salesman, of attempting to bribe a relative or his who was a juror in the aborted political corruption trial of Maryland Gov. Marvin Mandel.

The verdict came after slightly more than two hours of jury deliberately late this afternoon. Weikers sat stiff and impassive, his lips clamped tightly together, as the seven men and five women on the jury were individually polled.

In the middle of the rows of spectators behind him, his wife Mildred sniffed slightly and dabbed her eyes with a handkerchief. Her daughter by a first marriage is married to the son of Oscar Sislen, the Mandel juror that he attempted to bribe. Sislen was the chief prosecution witness in Weikers' trial.

Immediately following the guilty verdict, Assistant U.S. Attorney Barnet D. Skolnik asked that Weikners' $100,000 bail be revoked because, he said, the defendant might flee the area pending sentencing or appeal. Weikers' flight, Skolnik added, might be aided by "the individual, whoever it may have been, who got Mr. Weikers into this mess."

Prosecutors have contended, ever since a mistrial was declared last Dec. 7 in the political corruption trial of Mandel and four codefendants because of alleged jury tampering, that an unknown individual masterminded both the Sislen bribery and one other attempt to tamper with the trial.

"That individual," Skolnik said today, ". . . might find it in his interest to finance Mr. Weikers to leave the vicinity . . . (because) Mr. Weikers may now find it in his interest to talk."

The Mandel trial finally was aborted after several jurors in the case inadvertently heard a news bulletin about the Weikers bribery attempt and a tampering incident involving Mandel's attorney. The prosecutors quickly developed their theory that a "shark" was trying to subvert that trial.

Today's final prosecution argument was the first reference Skolnik has made to the "shark" during Weikers' trial.

"Somebody is pressuring Mr. Weikers to do what he is doing," Skolnik told the jury. "It's not his money. It's not his plot to subvert the Mandel case. He's somebody's pawn, somebody's tool. Somebody's using him.

". . . (Weikers) was pressured unmercifully by someone to do a terrible thing," Skolnik said.

U.S. District Court Judge Frank A. Kaufman denied Skolnik's request to remove Weikers' bail. "I don't see any danger of the defendant fleeing the community at this time in this case," he said.

Weikers faces a maximum penalty of five years in jail and a $5,000 fine.

As Weikers waited on the first floor of the courthouse shortly after the verdict today, the short, graying German immigrant exhibited the only emotion he has shown during the five-day trial, crying for a few seconds before he composed himself and went out to face the phalanx of television cameras and reporters waiting outside.

Weikers left the courthouse accompanied by his wife; his daughters, Susan Weikers and Barbara Friedman, his son, Clark; son-in-law Stanley Friedman and defense attorney Harold I. Glaser.

Glaser was the only one in the group to comment on the verdict, and said he had "no complaints against Judge Kaufman or the court system." Glaser said it was to soon the comment on whether the jury's verdict would be appealed.

Until today, the only reference to the possible instigator of the bribe Weikers offered to Sislen was contained in one of the key pieces of prosecution evidence: a tape recording of a Nov. 30 meeting between Weikers, Sislen and Sislen's wife Dorothy.

During this meeting, which took place in Sislen's car, outside the suburban Baltimore furniture store where Weikers works as a salesman, Weikers spoke of a "third party" who knew of the bribe attempt.

Skolnik said today that Sislen and his wife "are heroes" for cooperating with the prosecutors and turning in Weikers. "What they did," Skolnik said, "was about as rough a thing as any of you will be called to do in your life. They didn't enjoy what they had to go through this week."

Sislen, a chauffeur for a rental limousine company, lives with his family in Bethesda.

Glaser, Weikers' attorney, sketched a different picture of the Sislens in his closing statement to the jury than that painted by Skolnik. Oscar Sislen's story, he said, was "balderdash. Nonsense. Total and utter nonsense."

Referring to Weikers' failure to contact Sislen until a week after their first meeting on Nov. 23, Glaser said: "If you're going to take this most dangerous action - push."

The defense attorney added: "The pattern (of events) shows truth in what Oscar Sislen is saying.

Both the defense attorney and the prosecution agreed on most of the events and their sequence in the case. That Weikers called the Sislens' on Nov. 18, asking for Oscar, who was not home; that Sislen returned the call that night and Weikers told him to call back a few days later; that five days later the two men spoke on the phone and set up a meeting for that evening.

The two sides also agreed that Oscar Sislen suggested the meeting place - the roadside by a cloverleaf where I-95 and the Baltimore Beltway intersect. On every other aspect, however, the stories of Weikers and of the Sislens were diametrically opposed.

Sislen testified that during that twilight meeting, Weikers offered him a $10,000 bribed "To hold up the jury," by voting for the acquittal of Mandel.

Weikers insisted to the jury that Sislen had solicited the $10,000 bribe and that he only played along with his relatives - never intending to procure the money or give it to Sislen, firmy telling Sislen that he wouldn't.

"I didn't want to let him down," Weikers said repeatedly from the witness stand.

Weikers also contended that the entire sequence of phone calls and meetings had been started by a phone call from Sislen to him on November 18.

During his testimony in the trial, Sislen said that he took information about the telephone call to the Mandel trial judge and at the urging of authorities, agreed to record the meeting with Weikers. Leading the authorities to the person who orginated the bribe attempt, Sislen thought, would help his relative.

"We never wished Mr. Weikers any kind of harm and we never have," Dorothy Sislen testified.

At the end of the tape of the meeting between the two in the Fradkin Bros. parking lot - after Weikers had left the car - Sislen can be heard murmuring, "Very foolish, Walter."

A separate tape, originally scheduled to be played to the jury today by the prosecution was not played. The additional tape, also made during the parking lot meeting, was apparently intended by the prosecution was not played. The additional tape, also made during the parking lot meeting, was apparently intended by the prosecution to rebut Weiker's claim that the incriminating remarks he made in initial recorded conversation with the Sislens were the result of Oscar Sislen's coaching. The prosecution apparently decided that the Sislen's testimony and the other tapes were sufficient evidence against Weiker.

While he refused to revoke Weiker's bond yesterday, Judge Kaufman ordered Weikers to stay in the Baltimore area until his sentencing at a time not yet determined.

Kaufman also said he would carefully study a presentencing report on Weikers, which says Weikers has never been convicted of any crime, even a traffic violation, and a medical report ourlining the 67-year-old man's heart.