As the story of secret U.S. dealings with Iran leaked out last November, former national security adviser John M. Poindexter was at the center of administration attempts to hide the U.S. role and distance the president from the politically embarrassing operations, according to documents and testimony gathered by the congressional Iran-contra panels.

Many questions have been asked of Poindexter about this pattern of deception, but they have not focused on the full story of how the president and his staff, beginning on Nov. 5, initially attempted to keep events hidden, and then sought to limit what Congress and the public learned.

Rear Adm. Poindexter, who completes his testimony this week, has not been pressed in public sessions to disclose who initiated this now well-documented attempt at concealment, or to learn who, if anyone, coordinated it.

Nor have the committees asked the questions that might begin to solve one of the last great mysteries of the Iran-contra affair: Once the cover story that was given to Congress and the American people fell apart, did senior officials develop a new cover story about the role of Poindexter and his aide Oliver L. North -- one that is still operative today?

One event that has emerged as the "poison fruit" of the Iran-contra scandal was Israel's Nov. 25, 1985, transfer of 18 U.S.-made Hawk antiaircraft missiles to Iran using Central Intelligence Agency help and a plane leased from a CIA-controlled airline. (Details on Page A4.)

That operation, of which Congress was not notified, and which was approved by the president only after the fact, had been on shaky legal ground. And as the story of American dealings with Iran began to break early last November, U.S. involvement in the 1985 Israeli shipment of Hawks confronted the administration with a painful dilemma.

The CIA's participation was covered by a presidential authorization that Poindexter testified President Reagan signed Dec. 5, 1985. But this "intelligence finding," required by law for any U.S. covert action, defined the scope of the operation simply as "hostage rescue -- Middle East," narrow language that undermined Reagan's statements then and later that the United States never swapped weapons for hostages.

According to Poindexter, the document's potential political embarrassment to the president was so great that Poindexter tore it up and put it in a burn bag. He did that, he said, last Nov. 21. That action, which he said he took without consulting the president, came after a late-morning meeting with Reagan and Attorney General Edwin Meese III at which the president authorized Meese to try to clear up different accounts of the November 1985 Hawk shipment.

That same morning, Poindexter had told members of the House and Senate intelligence committees, it was unclear whether U.S. officials knew that any arms were in the November 1985 shipment at the time it occurred, a statement refuted by the finding he destroyed.

Poindexter's destruction of that document "solved" the political problem, but created another one: It obliterated the only legal authority for a November 1985 arms transfer that had always been on shaky statutory ground.

Without an intelligence finding, Justice Department lawyers previously had advised the White House, the Arms Export Control Act prohibited a foreign recipient of advanced U.S. weapons such as the Hawks to transfer them to a third country unless the executive branch notified Congress. Also, the act required the third country to certify in writing that it would use the weapons only in self-defense, something Iran clearly was not willing to do.

To conceal any U.S. role in that and an earlier shipment, and to distance the president from it once its existence became known, senior officials falsified chronologies, lied to Congress, withheld information from the attorney general and made misleading public statements, according to testimony or documents obtained by the congressional panels.

Between Nov. 4, when the first published reports of the U.S.-Iran arms shipments appeared in the United States, and late December, when an independent counsel began investigating criminal wrongdoing, misleading or incomplete accounts of the 1985 shipments, particularly the Nov. 25 Israel-Iran arms transfer, were given to Congress or the public by Reagan, chief of staff Donald T. Regan, Meese, the late CIA Director William J. Casey, Secretary of State George P. Shultz, Defense Secretary Caspar W. Weinberger, former national security adviser Robert C. McFarlane -- Poindexter's predecessor -- and Poindexter, according to the testimony and documents.

Regan, Meese, Shultz and Weinberger have yet to testify. But before they do, there will be further opportunity for the committees to ask Poindexter, who was involved more directly, some of the main outstanding questions.

Who sent Marine Lt. Col. North to Geneva on Nov. 8 to make a last-ditch effort with a new channel of Iranian government representatives to get more hostages released? What negotiating instructions did he have? Poindexter testified last week that his "best recollection" was that Reagan had approved the nine-point plan negotiated secretly with the Iranian representatives the previous month. It included U.S. positions contrary to stated American policy, including support for the removal of Iraqi President Saddam Hussein.

What was said at a meeting of high-level White House officials Nov. 10, a day after North's Geneva talks failed? The White House meeting was attended by Reagan, Vice President Bush, Regan, Meese, Casey, Shultz and Weinberger. It was the first such high-level meeting since the previous January to discuss the Iran initiative. Notes of the meeting taken by Alton G. Keel, acting deputy at the NSC, provide "some insights," according to the Tower review board, which did not elaborate.

In particular, did Poindexter give the Reagan Cabinet an accurate account of the 1985-86 initiatives with Iran?

On Nov. 18, Poindexter and others met with the president to go over practice questions for Reagan's news conference the following night. How did Poindexter prepare him for questions about the 1985 Israeli shipments that had been mentioned in the news for more than a week?

Specifically, did Poindexter read the president the practice questions and answers prepared by North, which included: "Did the U.S. government authorize Israel to ship military equipment to Iran in our behalf?" and was followed with the accurate "practice answer" that "on two specific occasions I authorized an exception to policy by permitting a small amount of defensive military equipment to be transferred to Iran by a third country."

What was said at a two-hour Nov. 24 White House meeting, attended by Reagan, Bush, Casey, Shultz, Weinberger, Regan and Poindexter? Then-White House spokesman Larry Speakes said the topic was "Middle East policy." But the context was extraordinary. It was immediately after this meeting that Meese informed Reagan and Regan that his aides had discovered the explosive "diversion memo," which tipped them off about the scheme to divert profits from the U.S.-Iran arms sales to the Nicaraguan rebels.

Why did Poindexter resign? In explaining to the committees why he agreed to resign Nov. 25 after Meese suggested he do so, Poindexter said that beginning with the diversion that February, it had always been assumed that he would do this if the operation was disclosed. Assumed by whom, other than Poindexter? Poindexter testified he never discussed his decision to authorize the diversion with Reagan, Casey or Regan, and he believed only North knew of it in the government.

No one has more detailed knowledge of the White House's initial reaction to the disclosure of the Iran dealings than Poindexter.

On Nov. 4, for example, Poindexter called McFarlane and told him there would be no comment on the news story from Beirut that described, somewhat inaccurately, McFarlane's trip to Tehran, according to the Tower board.

Two days later, however, at a bill-signing ceremony in the White House, Reagan went beyond "no comment" and made the first high-level misstatement: He said there was "no foundation" to the story published in Beirut.

One justification administration officials have used for putting out a cover story in those early days was the need to protect their Iranian intermediaries, now known to be associates of the speaker of the Iranian parliament, Ali Akbar Rafsanjani. That argument appears less credible in light of disclosures that the Iranians not only had obtained badly needed U.S. weapons, but also the U.S. nine-point plan, which secretly gave them major concessions. There have been no reports of any reprisals against Iranians involved in the secret deals.

Still only superficially explored by the committees are the details of the internal dealings between Poindexter and key members of the Cabinet as the scandal unfolded.

On Nov. 12, Assistant Attorney General Charles J. Cooper, by his testimony, conferred with Poindexter and a NSC legal officer, Cmdr. Paul B. Thompson. Thompson took from a "secret place" a Jan. 17, 1986, authorization, signed by Reagan, for the direct U.S. sales to Iran in 1986. But he made no mention of the earlier finding that Poindexter said was in his safe.

That day produced the first signs of disarray in the administration over the official story of what happened, with White House spokesman Speakes saying Meese had provided legal advice on U.S. dealings with Iran since mid-1985, and a Meese spokesman denying that.

On Nov. 13, Reagan addressed the nation on the burgeoning scandal, and made many misleading statements.

On Nov. 18, Reagan prepared for his news conference the next day. The notebooks of North, and the typed practice questions, make clear that North and Poindexter had the facts about the 1985 shipments and well understood their serious implications. If Poindexter went over the questions and proposed answers with Reagan, it would suggest that he also understood them. Yet Reagan denied at the news conference that the United States condoned any third-country shipments to Iran, and the White House had to issue a correction that still did not made clear what had occurred.

Poindexter has told the committees that on Nov. 21, North showed him one of his old spiral notebooks with an entry noting that Reagan had directed the Hawk operation to proceed in 1985. Poindexter had the impression North was going to destroy the notebook, he testified.

Meanwhile, Poindexter destroyed the finding, thus apparently removing the last documentary links between the president and the Nov. 25, 1985, Hawk shipment. In fact, North did not destroy his notebook, and the CIA retained an unsigned, draft copy of the finding.

One of the most intriguing mysteries of last November was the publication of a detailed and accurate story in the Los Angeles Times on Nov. 27, just two days after Poindexter resigned and North was fired. It reported that North had destroyed NSC documents relating to Iran the previous weekend.

The story was true, although the White House denied it at the time.

Did someone in a high place in the Reagan administration leak that story to expose a conspiracy at the highest levels to cover up the truth?