The scandal and murder that tore asunder the Charles Von Maxcy family 35 years ago reverberates still. Monday, the dead man's daughter will sit in a federal courtroom in Fort Pierce, praying for a Death Row convict.

``I know Billy Kelley didn't kill my father,'' said Marivon Adams, whose Maxcy relatives refuse to speak to her.

Their opinions are superfluous. The critical legal issue revolves around one question: Was there prosecutorial misconduct?

If U.S. District Court Judge Norman G. Roettger, a Nixon appointee who has conducted only one previous evidentiary hearing during his 29 years on the bench, answers that question in the negative, Kelley, a two-bit Boston crook, will be immeasurably closer to a lethal dose of potassium chloride. If the answer is affirmative, Kelley could walk out of prison a free man. The lone witness who claimed he hired him as a hit man is long since dead. There never was a shred of physical evidence.

That witness was John Sweet, who also served time for the homicide of Charles Von Maxcy, 41, a Sebring cattle baron who was knifed in the back and shot in the head.

Sweet set it up. Two killers took care of Maxcy in the bedroom of his sprawling ranch house on a warm October night in 1966.

Sweet wanted Maxcy dead so he could sleep in his French Provincial bed with his rich widow, Irene. He had his way for a year after the murder -- much to the chagrin of the Maxcy clan.

Then, Irene testified against Sweet and he got life -- that is, until Irene went to prison for lying on the stand. She was also sleeping with the chief homicide detective.

IMMUNITY DEAL

A few years later, no one was in prison for the murder of Maxcy. This infuriated the Maxcy family. Then, in 1981, 15 years after the murder, police in Massachusetts charged John Sweet with a slew of felonies and he went to the police and fingered Billy Kelley, along with a deceased mobster, in exchange for immunity.

``We sat through the trial and thought Kelley was guilty,'' said Guy Maxcy, the dead man's nephew.

The Maxcy family went to both of Kelley's trials -- the first ended in a mistrial and the second in a death sentence for Kelley.

The difference?

At the first trial in 1984, Highlands County prosecutor Hardy Pickard, a laconic Southern gentleman, told jurors about the immunity deal when Sweet handed over Kelley. At the second trial two months later, nary a word -- not even from the defense.

These days, Kelley, 58, sits on Death Row at Union Correctional Institution in Raiford with a lot of time on his hands. He even charts the temperature in his cell. Once it hit 110 degrees.

``It's very rare to get such a hearing in federal court, and I'm so thankful,'' he said. Among his appellate lawyers are Jimmy Lohman, a New Orleans capital crimes specialist, and Laurence Tribe, a Harvard constitutional scholar.

In Boston in May, Roettger heard attorneys and police tell how they struck the immunity deal for Sweet's testimony about Kelley.

To the jury in 1984, prosecutor Pickard declared: ``John Sweet did not have to give the police Kelley to get immunity. . . . It has nothing to do with the Maxcy case or giving them Kelley on the Florida case.''

NEW WITNESSES

Beginning Monday in Fort Pierce, Roettger will listen to more witnesses -- among them prosecutor Hardy Pickard. He has never spoken publicly about his comment, never been cross-examined.

Roettger will have to decide if there was prosecutorial misconduct, if Pickard misled jurors, and if Kelley should get a new trial. Such a trial -- with Sweet dead and no evidence -- would be almost impossible to conduct. But Assistant Attorney General Carol Ditmar is confident that another trial will be unnecessary.

Irene Maxcy, the widow of Von Maxcy and former mistress of Sweet, will not attend the hearing.

``It is all very upsetting to my mother,'' said Adams, 41. ``She is elderly, frail and very tired.''

Billy Kelley won't be there either. He'll listen from a phone on Death Row at Raiford -- in an air-conditioned office.

Jimmy and Guy Maxcy, the nephews who for years wanted Kelley executed, also won't make it. ``It's in God's hands,'' Jimmy Maxcy said.

And what if Billy Kelley walks? ``We believed in the judicial system when he was convicted and put on Death Row; we'll believe in it now if he gets off.''