Before the state takes a life, which it does in your name and mine, it should be clear to a moral certainty that the prisoner is guilty and that he is among the worst of the worst.

Florida has been moving in that direction for a long time, but we're not there yet. A case in point is that of Michael Lambrix, who was condemned 20 years ago for the deaths of a man and woman near Fort Myers. The state claimed he killed them to take their car. His story is that the man killed the woman and that he killed the man while trying to save her. For reasons that only lawyers understand, Lambrix has never been able to tell it to a jury.

He was once a day away from the electric chair when a stay came through. Later, the U.S. Supreme Court said that sentencing proceedings like his weren't fair, but when he asked for the same break the court held 5-4 that because he had already lost his direct appeal the "new rule" did not apply.

A few months after that, the Florida Supreme Court ruled against him a seventh time and he wanted a new lawyer. So he wrote to Gov. Lawton Chiles. Sign my death warrant, he said. Set my execution date. That will make them find me a new lawyer.

When I last wrote about him, it was to deplore the inhuman hypertechnicality of a judiciary that would let one man die under circumstances identical to those under which it spared another.

The Lambrix case has now taken an even stranger turn.

It brings to mind why smart cops and prosecutors have a saying that to sleep with a witness is to mess up the case. (That is not the precise phraseology, but this is a family newspaper, not the well of the U.S. Senate.)

At a hearing before a circuit judge three months ago, a witness who was instrumental in sending Lambrix to death row said under oath that she was having a brief affair with a lead investigator during the prosecution. The witness, Frances Smith-Ottinger, had been Lambrix's girlfriend, was caught driving the stolen car, and for a time was a suspect herself.

No one else knew about the alleged affair when Lambrix was tried. Had his attorneys known, they could have used it to attack her testimony. The average time from conviction to execution is 11.85 years, and if the state had succeeded in killing Lambrix that quickly no one would know now.

"There were some rumors about this that came to light," says Dan Hallenberg, Lambrix's lawyer from the Capital Collateral regional office at Fort Lauderdale. "We simply asked her, I expected her to deny it, everybody's mouth dropped open."

What's more, there's a second witness who says under oath that she lied at the trial to make it look as if Lambrix killed in cold blood to steal the car. That witness, Deborah Hanzel, says in a sworn affidavit that she lied about what Lambrix told her in a telephone conversation. She says she lied because Smith-Ottinger put her up to it.

"Because of the stories the police and Francis Smith were telling me about Mr. Lambrix," she said in an affidavit, "I was convinced that he likely would come after my children and me . . ." So she let Smith persuade her to "back up her story by telling the police that Mr. Lambrix told me that he killed the people in order to steal their car. . . .

"When I asked Frances if that was what really happened, she told me she didn't really know what happened outside but that Mr. Lambrix had told her that the guy went nuts and he had to hit him."

It would be an understatement to call this a messed-up case. With so much in doubt about it, how could anyone still insist on Lambrix's execution?

Yet the game goes on. The state is concededing nothing. From its viewpoint, witnesses who say now that they were lying then could as easily be lying now.

"I don't think the taxpayers would want to pay for an entire new trial when there was no constitutional error committed in the trial in 1984," says Carol Dittmar, the assistant attorney general in charge of the case. "If you give him a new trial, you're giving him a chance to litigate another 20 years in postconviction. I don't think that's a good way to spend taxpayer money."

Maybe not. But if the judge decides that Smith-Ottinger is telling the truth about the affair - the former investigator, Robert Daniels, hasn't been heard from yet - it seems to me there would remain only one decent alternative to a new trial. That would be to offer Lambrix a plea bargain. His case has its own holes, chiefly that he did bury the bodies and did take off with the car. His excuse, that he was technically an escapee, having walked away from a work release center on a forgery conviction, might not be persuasive with a jury.

But neither does it prove that he killed in cold blood, or that this case merits the death penalty more than the 99 percent of homicides in which it is not sought or imposed.

It is cases like this that reiterate a fundamental question: Is capital punishment worth whatever good anyone thinks it does?