Washington ? Dealing with the devil is an old and at times necessary diplomatic tactic. But dealing with the devil’s public relations advisers and international lawyers to help him protect his image? That has to go beyond the pale.

To get information and help against al Qaida, the Bush administration may soon participate in the political rehabilitation of Libya’s Moammar Gadhafi, overseer of terror plots that killed hundreds of Americans and Europeans and butcher of political dissidents at home. Time and the escalation of Middle Eastern terror tactics have made Gadhafi yesterday’s devil.

Without knowing what Gadhafi claims he will provide against Osama bin Laden, it is difficult to judge the convoluted plea bargain that U.S. diplomats have helped broker to close the books on Libya’s now nearly acknowledged bombing of Pan Am 103 in 1988.

But if Gadhafi’s regime does not accept in clear and binding terms its responsibility for the murder of 270 people over Lockerbie, Scotland — and name the operatives who carried it out — this will be a flawed deal that will not justify the lifting of U.S. and U.N. sanctions against Libya. Morally, that price is too high.

The normally reclusive Gadhafi has given recent interviews to print journalists and on American television that walked to the edge of acknowledging his crime, but then stopped short of that Perry Mason moment. His lawyers will no doubt want to sell Washington an evasively worded “confession” that will leave Gadhafi room to tell future interviewers that he confessed to nothing.

Unlike interviews I had with him in the years before Pan Am 103, in the recent sessions the Libyan leader appeared to have been coached to keep his on-screen answers short and noncommunicative. His ramblings and tirades about the evils of Ronald Reagan, alcohol and Egypt’s leaders were under control this time. Physically, he did not appear to be nearly as haggard and disjointed as he did in my last encounter with him in 1987.

But coincidence can complicate the rollout of any PR offensive. As Gadhafi was trying to change his spots on camera, hundreds of pages of documents that give stomach-churning insight into his past terror operations were being filed in U.S. District Court in Washington. The American lawyers and diplomats who have been working with the Libyans on the Pan Am 103 deal should be required before they sign anything to read the entire file of this case, which will receive its first court hearing before Judge Thomas Penfield Jackson on Sept. 9.

The most important of these documents come from France’s top antiterror magistrate, the redoubtable Jean-Louis Bruguiere, whose investigation led to the conviction in absentia of six Libyan intelligence officials in 1999 for the Sept. 21, 1989, bombing of a French UTA airliner over Niger. All 170 persons aboard UTA flight 772, including seven Americans, were killed in circumstances that mirrored Pan Am 103.

These legal briefs, filed by attorney Stuart H. Newberger in a civil suit against Libya on behalf of the families of the seven American UTA victims, read more like a novel than a pleading.

Shadowy Congolese agents trained in explosives by the Libyans, who seek vengeance for France’s role in Chad, move through these complaints and motions like characters out of John Le Carre. More importantly, the ways in which the region’s different terror networks — Libyan, Palestinian, Syrian, et al — cooperate to thwart investigations and retaliation come into sharp focus.

So do Libya’s clumsy efforts to lie to Bruguiere and cover up the UTA plot, which was directed by Gadhafi’s brother-in-law, Abdullah Senoussi. But Bruguiere’s tenacity finally produces the in-absentia convictions through a legal process that Gadhafi formally accepts in a letter to President Jacques Chirac reproduced in this file.

“We believe these documents help establish that there can be true accountability based on forensic proof and testimony in court about Libya’s legal responsibility for this act of murder,” says Newberger.

That should be a minimal standard as well for the Pan Am 103 case, which Libya has always sought to handle as a public relations problem rather than the crime it is. Gadhafi hired American publicists and encouraged British businessmen to blame Pan Am 103 on Palestinians, Syrians, et al. — to no avail.

Sanctions have worked, and are working, in this case. Gadhafi is jumping through hoops to get them lifted. President Bush should not bless any deal to end the sanctions that does not include a clear admission by this particular devil that a Libyan plot carried out by his agents destroyed Pan Am 103. History and justice demand nothing less.