"He approached me, I didn't approach him. He called me.I didn't call him."

Biting out those words near the end of the 2 1/2 hours he spent on the witness stand today. Walter Weikers heatedly denied that he had offered to bribe Oscar Sislen, a relative by marriage and a juror in the political corruption trial of Maryland Gov. Marvin Mandel.

Continually during his appearance on the stand - an appearance that twice had to be interrupted when Weikers, who has a heart condition, appeared to be in pain - the 67-year-old German immigrant said he played along with Sislen for a time "because I didn't want to let him dowm . . . he was very desperate."

Weikers has been charged with offering Sislen, his stepdaughter's father-in-law, a $10,000 bribe to keep the jury from convicting Mandel or one or more of the Governor's codefendants.

A mistrial was declared in the Mandel case on Dec. 7 after several-jurors inadvertently heard a television news bulletin about that alleged bribe attempt and another alleged attempt to fix the trial.

Weikers took the stand in his own defense this afternoon shortly after the final piece of prosecution evidence, the tapes and transcripts of two converstations between Weikers, Sislen's wife were played to the jury during the second day of testimony in the case.

On one of the tapes, recorded on the afternoon of November 30 by a tape-recorder hidden under the seat of Oscar Sislen's car, by investigators Weikers could be heard telling Dorothy Sislen, "If he (Oscar) wants me to go ahead and get the goods, say yes. The other way, say no . . . It's between you and Oscar and me and nobody knows it."

Later in the conversation, Weikers said, "One, one juror, all he has to say is no. That's all." At another point Weikers could be heard saying. "How's (Sislen) gonna get caught? He just holds out for . . . acquittal. That's all. For not guilty."

On the witness stand, Weikers said that any reference he may have made to getting "the goods" on the tape or to Sislen's voting for acquittal was made on Sislen's instructions, to placate Mrs. Sislen.

Before that conversation, Weikers testified, Sislen had told him, "My wife is out in the car; she's very worried about it, just tell her I'll be in no trouble."

Defense attorney Harold I. Glaser, then asked, "Why did you tell that to Dorothy?" and Weikers answered, "Because - Mr. Sislen, I didn't want to let him down."

Weiker's contention that what he said in the car was only what Sislen told him to say is directly contradicted, however, by another prosecution tape that has not been played, but is expected to be the core of the prosecution's rebuttal arguments tomorrow.

Before the conversation in the car November 30, Sislen and Weikers had talked inside Fradkin Bros. Furniture Store in suburban Balitmore, where Weikers worked.

Sislen was equipped with a body microphone and federal agents planned to monitor and record the conversation, but apparently the store's fluorescent lignts interfered with much of the transmission.

After he came out, Sislen conferred with agents, who told him of the problem and asked him to get Weikers out to the car again on some pretext so a clear recrding could be made.

Sislen then went back into the building and asked Weikers to come out; it was during this brief portion of the conversation, Weikers claimed, when Sislen coached him on what to tell Dororthy Sislen.

However, according to a transcript of the tape made of that conversation inside that prosecutor Barnet D. Skolnik read outside of the presence of the jury yesterday, Sislen gave Weikers no instruction at all. Instead, he merely told Weikers that he had told his wife about the bribe, and asked Weikers to reassure her.

Weikers appeared visibly tense and nervous during his period on the witness stand. During the first 15-minute recess he requested, his wife Mildred and his daughter Susan rushed to join him in the witness room where he took some medication, according to defense attorney Glaser. The playing of the tapes had ended the prosecution's original presentation at noon today.

Wednesday, both Sislen and his wife had taken the stand to tell of the sequence of phone calls and meetings that began November 18, including a roadside meeting with Weikers on November 23, and ended with the meetings at Fradkin Bros. and in the car November 30.

Weikers was arrested a few hours after his final meeting with Sislen. That evening, prosecutors asked Weikers the identity of the "fourth party" he had referred to in the car conversation with the Sislens.

In that taped conversation with Sislen, Weikers said, "I don't get nothing out of it, I'm sorry I was approached." Later he added, "But to be only betqeen you (Mrs. Sislen) Oscar and the third party don't . . . the fourth party don't even know youL"

When the prosecutors asked him about this, Skolnik told the judge outside the jury's hearing today, Weikers said he had been approached by "a stranger." Then, on Glaser's advice Weikers refused to say any more to the prosecutors. He has not cooperated with the prosecution since that time.

The case is expected to go to the jury tomorrow.