BY GAIL EPSTEIN NIEVES AND ALFONSO CHARDY

 A Miami federal jury on Friday hammered five Cuban intelligence agents with across-the-board guilty verdicts on 23 spying-related charges -- a
 stunning decision that overwhelmingly endorsed U.S. efforts to sanction Fidel Castro's government not only for espionage but for the murders of
 four Brothers to the Rescue fliers.

 Relatives of the Miami men who perished in the 1996 Brothers shoot-down by Cuban fighter jets quietly rejoiced as a courtroom clerk read
 aloud the "guilty'' verdict for the count of murder conspiracy, returned against spy master Gerardo Hernández.

 Maggie Khuly, the sister of shoot-down victim Armando Alejandre and a devoted note-taker during the six-month trial, doubled over in her seat.
 Mirta Costa Mendez, sister of victim Carlos Costa and another trial devotee, threw her left arm over Khuly's back in a warm embrace.

 "A sweeping win, a sweeping victory for the United States of America and for these families standing behind me,'' proclaimed U.S. Attorney
 Guy Lewis, flanked on the courthouse steps by some of the victims' relatives and a jubilant prosecution team: Assistant U.S. Attorneys Caroline Heck Miller, John
 Kastrenakes and David Buckner, and FBI agents Al Alonso and Jose Orihuela.

 "Gracias a Dios,'' (Thanks to God),'' said Eva Barba, mother of deceased flier Pablo Morales. "This is what I have been waiting for. This is justice.''

 The five defendants and their lawyers -- who had been expecting at least partial acquittals from a jury with no Cuban Americans -- grew increasingly solemn and fidgeted in their chairs as the verdicts unfolded.

 3 COULD GET LIFE

 Three of the men -- Hernández, Ramón Labañino and Antonio Guerrero -- face maximum sentences of life in prison. Two others -- Fernando González and René González, who are not related -- face maximum penalties of 10 years behind bars.

 U.S. District Judge Joan Lenard set a separate sentencing for each defendant on Sept. 24-26 and 28, and Oct. 2.

 The verdicts were pronounced at 5:09 p.m. to a packed courtroom in downtown Miami. The decision ended a complicated trial that provided unprecedented peeks into Cuba's enduring Cold War-era spying mentality -- a mind-set in which defending Castro's "revolution'' was a noble cause to be accomplished with technology, lies, manipulation -- even murder.

 The verdicts were the first legal determination that the four Brothers victims were indeed murdered -- "the unlawful killing of human beings with malice aforethought,'' the indictment states -- even though the term has been used since the start.

 There was no official reaction from Havana late Friday.

 The five men were among 14 people originally arrested in September 1998 as members of the La Red Avispa, the Wasp Network, the biggest Cuban spy ring known to have been dismantled in the United States.

 Evidence showed that ring members, some using fake identities, tried to infiltrate U.S. military installations and Cuban exile groups in an effort to feed military and political information back to Havana.

 In thousands of pages of decoded communications between Havana and the agents, the evidence showed they also were tasked with spreading disinformation about exile leaders, fomenting internal dissent within exile groups, sabotaging Brothers planes and ruining Cuban-American politicians.

 DEFENSIVE MISSION

 Defense attorneys disputed the charges. While they acknowledged that the men were Cuban intelligence agents, they claimed that they were sent to South Florida to
 protect Cuba from a U.S. attack and from "extremist'' Cuban exiles believed responsible for a series of hotel bombings in Havana.

 But most of the trial focused on the Brothers shoot-down, which defense attorney Paul McKenna blamed on the group's co-founder, José Basulto. McKenna called
 Basulto's repeated incursions into Cuban airspace "provocations.''

 Shortwave radio transmissions between the spies and their handlers in Havana showed that in the days leading to the fatal air attack, Cuba was preparing for a violent confrontation with Brothers' planes and even warned its Miami-based agents not to fly on the Brothers' planes.

 Prosecutors argued that the messages showed Gerardo Hernández had prior knowledge of the pending attacks, but McKenna said there was no proof. McKenna also argued unsuccessfully that the shoot-down occurred in Cuban airspace.

 After the verdict, McKenna said he was puzzled by the jury's decision and credited the government for including the shoot-down charge in the indictment. The murder conspiracy count, added to the case after the original indictment, was the most emotionally and politically charged accusation in the case.

 "It was a very complicated case,'' McKenna said. "The only thing I wondered about in my own mind was the jurors never had a question. But . . . in our system when they speak, the buck stops there.''

 Jack Blumenfeld, lawyer for Guerrero, said he thought the trial had ``turned in our favor, but I think there was just an overwhelming amount of evidence that the government had. I mean, for God's sake, they investigated this for years before they arrested anybody.''

 Jurors deliberated for 28 hours over five days. An amiable group, the members bonded so well that they could be heard laughing from their private room during trial breaks. They even had a pet fish, Larry, named for the chief court security officer in Judge Lenard's courtroom.

 No jurors could be reached Friday night.

 'INDICT CASTRO'

 Basulto and the Cuban American National Foundation applauded the verdicts and immediately reasserted their demands that the United States indict Fidel Castro for the shoot-down.

 "Brothers to the Rescue had nothing to do with this, even though in this trial they tried to blame us for this,'' Basulto said on the courthouse steps. ``Now we need the support of our community to ask the president of the United States . . . to indict Fidel Castro criminally, who is really the one responsible.''

 Joe Garcia, executive director of the CANF, said: ``There should be nothing standing in the way of prosecuting Castro. There is proof now that operatives of the Cuban government were involved in the murder of U.S. citizens.''

 Lewis, the U.S. attorney, would not comment on his office's plans regarding Castro, but said the investigation is continuing.

 "The evidence showed beyond any reasonable doubt that there was a conspiracy to murder these men, that one of the defendants in South Florida was involved in that conspiracy, that that conspiracy was hatched in Havana, in Cuba,'' he said. "The blame and the fault lies now clearly at the feet of the Cuban government.''

 WILL NOT STAND IDLE

 Lewis also said that while the case confirmed fears that many Cuban exiles have harbored for years, in the end, the FBI and his office protected the community from
 "Castro's tentacles.''

 "There have been spies among us,'' he said. "Let the verdict serve notice, though, we will not stand idly by and allow any foreign government to wreak its havoc upon our way of life.''

 Héctor Pesquera, head of Miami's FBI office, directed "a very special message'' to Cuba's leader, telling Castro that sending his agents to the United States "to conduct intelligence operations against the citizens of this country will not be tolerated.''

 Heck Miller, the lead prosecutor, paid emotional homage to the shoot-down victims as she addressed reporters after the verdicts.

 "This is a day of justice, a day of vindication of our justice system, of our jury system and I only want to say God bless the United States, God bless the memory of
 Carlos Costa, Armando Alejandre, Mario de la Peña and Pablo Morales.''

 Herald staff writer Carol Rosenberg contributed to this report.