For the past eight years, lawyers for two half-brothers sentenced to die for a woman's murder in Florida repeatedly tried to persuade judges that their clients, who came within 16 hours of execution four years ago, were wrongly convicted by a jury that was not presented crucial evidence.

This month a Florida federal judge agreed. He ordered a new trial for William Riley Jent and Earnest Lee Miller, whose case has been closely watched by death penalty opponents, some of whom said it was the most dubious death row conviction in Florida.

While not ruling on the innocence or guilt of the two men, U.S. District Court Judge George Carr in Tampa said the prosecutors had withheld "favorable evidence" from defense lawyers, evidence that came to light after two Florida newspapers successfully argued before an appeals court that the sheriff's reports on the murder should be released. Prosecutors, who had earlier persuaded a lower court to deny access to the records, made the reports public in 1986.

Among the records were two police reports that seemed to undermine the credibility of the prosecution's key witnesses. In one report, a witness who said she saw the two men kill the woman mentioned that her recollection could have been a dream. Another report had interviews with six potential witnesses whose testimony the defense contends would have bolstered Miller's alibi.

In ordering a new trial, Carr stated he found the failure of the prosecutors to provide the material to the defense "deeply troubling: by withholding such favorable evidence, the state has demonstrated a callous and deliberate disregard for the fundamental principles of truth and fairness that underlie our criminal justice system."

It is not unusual for death row inmates to be granted new trials because evidence was withheld from the defense.

"It's significant any time the defense catches the prosecution withholding information," said Richard H. Burr, the coordinator of the capital punishment project for the NAACP Legal Defense and Educational Fund. "When we do catch them, it's the tip of the iceberg . . . . The case of Jent and Miller is one of the most dramatic cases. The lies were so big."

From the beginning, the case was controversial. The murder victim was never fully identified. Key witnesses changed their stories. Some claimed they were pressured to recant. Law enforcement officials failed to pursue several leads.

The murder victim was finally identified in 1985 after a Washington Post reporter, who was investigating the conviction of Jent and Miller, linked a set of fingerprints in Tennessee of a missing woman, Linda Gale Bradshaw, to prints taken from the partially burned body of the murder victim. They matched. The Florida Department of Law Enforcement then conducted its own investigation and concluded that the victim was Bradshaw.

Defense lawyers claim that the identity of the murder victim is important to the case. They said the state will have to reindict Jent and Miller if it decides to hold a new trial because the two were indicted for killing a woman identified only as Tammy. Also, they said there is a witness who says he saw Bradshaw killed by her boyfriend, Charles Robert (Bobby) Dodd Jr.

The state attorney's office declined to comment on Carr's ruling, which could be appealed. Under Carr's order, the prosecution must begin proceedings for a new trial within 90 days of his Nov. 13 ruling or release the two men.