As political theater, the Billy Carter hearings have all the trappings: the bigname witnesses and their high-priced lawyers, the cavernous Senate Caucus Room bathed in kleig lights, the expectant audience drawn by the scent of scandal.

Beyond the media event, however, the investigation by a special Senate Judiciary subcommittee has yet to produce any significant evidence of misconduct. "I'll wager that 90 percent of everything we will hear, you have already written about," subcommittee chairman Birch Bayh (D-Ind.) told a group of reporters Friday afternoon.

But, he quickly added, "Until you stir the pot, you can't say whether you have a mouse or a dinosaur."

Such doubts about the nature of the animal have left the nine senators on the panel feeling slightly queasy. They have a commitment to see the thing through, and, each day, they face a battalion of television cameras. Under such circumstances, who would dare to say the emperor has no clothes?

"We're involved in it now," said Sen. Bob Dole (R-Kan.) in an interview yesterday. "We have our reputation to worry about. We've got to get the facts. We can't have a situation that, when it's all over, The Post, or The New York Times says why didn't you bring this or that out.Once you get into it, you have to be careful or you'll get hit with a falling object."

The pressure to come up with something juicy and the overwhelming media interest contributed to the sudden decision, at the beginning of Billy Carter's testimony Thursday, to release information that two of Carter's friends were under investigation by the government on suspicion of drug smuggling.

Bayh, while acknowledging that the allegations did not include Carter and were "irrelevant" to the hearings, said he had to release the information because a senator had received a press inquiry about it.

But the highly unusual decision to confront an unsuspecting Carter with the allegations during live television coverage only reinforced the impression that there was more sound and fury than substance in the inquiry so far.

The questioning of Billy Carter and his business associates during four days of hearings turned up a few new details: financial consultant Ronald C. Sprague had his picture taken with the president; Billy Carter may have once described the first payment he got from Libya as a reimbursement for expenses rather than a loan; a National Security Council official says he warned Billy Carter against going to Libya before his first trip, rather than afterwards, as Carter claims.

But the new information, while titillating to what may be a growing league of Billy buffs, was inconclusive. Moreover, the senators seemed to run out of questions early. Staff members complained they had not had enough time to obtain key documents and interview important witnesses before Carter was called. Several senators, embarrassed when Carter seemed to have plausible answers to everything, complained the investigation was being rushed.

"These witnesses are well coached," said Sen. Max Baucus (D-Mont.) during a break in the testimony. "I don't know if there's illegal or improper behavior, but I sense we're unable to sufficiently answer that question due to inadequate preparation."

Pressed by Baucus, Dole and Sen. Charles McC. Mathias Jr. (R-Md.), Bayh postponed this week's hearings to give the staff more time to investigate. But facing pressure to wrap up the inquiry before Election Day and worried about his own reelection campaign, Bayh is none too pleased about the delay.

"I sense that being better prepared in the view of some senators means being prepared to disclose a great big whopper that may not be there," Bayh said. "I prefer to dispose of this before the election. I'm not prepared to keep hacking it to death right up until people got to the polls."

Nonetheless, Bayh acknowledges it is a "delicate balance. I don't want us to be accused of a cover-up. It's better for justice to be done between Nov. 15 and Dec. 15 than injustice on Oct. 4," the date the Senate has set for a subcommittee report.

In the face of the canny, noncommittal responses of Billy Carter and his friends, the senators made the best of it, competing gamely as to who could display the most outrage and, coincidentally be featured in the evening news.

Reminding Billy Carter repeatedly that the Libyans had harbored the murderers of Israeli Olympic atheltes, had attacked the U.S. Embassy in Tripoli and had ordered assassinations of dissident Libyans in Europe, Sen. Richard G. Jugar (R-Ind.) asked, "How in the world could you have continued business negotiations if you knew the Libyans were undermining the Camp David accords? How could you in conscience continue negotiating with that government?"

Carter, who registered as a foreign agent in July, received $220,000 from the Libyan government that he said was a loan, and was negotiating for a million-dollar oil allocation that never came through.

He has said the Libyans were helping him out of friendship and concern that his income from public appearances dried up after he hosted a Libyan trade delegation in Georgia and made some anti-Zionist remarks.

At one point, obviously impatient with the line of questioning, Carter told Lugar, "Senator, I feel a lot safer in Tripoli than I feel in Atlanta, Georgia, at night walking the streets."

Lugar also suggested that President Carter was intentionally helping his brother's business relationship by inviting the Libyans to the White House to discuss the Iranian hostage situation. He used the analogy of the banker J. P. Morgan, who once told a supplicant he would walk around the block with him so others would see the association and lend him money.

Sen. Strom Thurmond (R-S.C.) questioned Billy Carter as to how he could become "in debt to this government which has engaged in terrorism and assassination."

Nor were the attacks merely from the Republican side of the aisle. Sen. Patrick J. Leahy (D-Vt.) told Carter that "far more important than the discomfiture to you is the damage that has been caused to the president of the United States and to the country itself."

Leahy said he sympathized with Billy Carter's loss of privcy and financial and medical problems, "but a lot of it you brought upon yourself" be encouraging "commercial exploitation," Leahy said. "A lot of people were out to use you. Quite frankly, you could have stopped it and didn't."

Baucus asserted, "I think it is clear that a loan to the brother of a president from a radical, terrorist country does potentially compromise the president."

Although Carter and his lawyers were exasperated by the lectures, Carter kept his cool throughout the two 6-hour days of questioning. In the end, he admitted that if he had to do it all over again, he would think long and hard about going to Libya. "But hindsight ain't worth a damn," noted the man who was once the nation's favorite "good ole boy."

And, at the end of the week, the senators had to admit they did not really have anything on him -- or on the administration. "I don't think we will have failed if, when it's all over, we don't have five carcasses nailed to the wall," Bayh said. "What Billy Carter did is totally irresponsible, but that doesn't make it illegal."

Some senators even seemed to feel sorry for Carter, whose life was disrupted by his brother's fame."Pity the well-connected," sympathized Mathias, recalling a line from Gilbert and Sullivan.