BY CAROL ROSENBERG

 A Cuban prisoner now being held in a Louisiana jail was promised safe passage
 to his homeland by federal authorities in exchange for ending a six-day prison
 uprising, a copy of a letter on Justice Department stationery shows.

 Roberto Villar Grana, 31, is one of seven Cuban prisoners listed by name in the
 official offer, a copy of which was obtained Thursday by The Herald.

 ``All instructions of the Federal Bureau of Investigation must be followed in order
 to ensure the safe passage for each of you,'' the letter said.

 The inmates released the hostages, following the instructions.

 But instead of safe passage, Villar Grana was removed from a Cuba-bound prison
 service plane minutes before it took off Monday. He was handed over to Louisiana
 officials, according to federal sources, because local authorities alleged he raped
 a female inmate during the uprising.

 But St. Martin Parish Sheriff Charles Fuselier denied Thursday that he had made
 such an allegation.

 ``I don't know where that rape came from; we have no evidence of it,'' he said.

 The sheriff added angrily: ``I did not put him on the plane. I did not take him off. I
 didn't have him taken off.''

 The letter raised the question of whether FBI and immigration service agents
 misled Villar Grana's mother, Mercedes Villar, when they asked her to vouch for
 the safe passage offer.

 Her son was in the Calcasieu Parish jail in Louisiana on Thursday while the six
 others who were returned to Cuba were reportedly in jail in Havana.

 Villar Grana is facing sentencing Jan. 6 on an earlier conviction involving a
 high-speed car chase, while St. Martin's Parish prosecutors plan to indict him for
 aggravated kidnapping in the jail takeover. Both crimes are punishable by life in
 prison. Prosecutors in both counties said they would seek to jail him in Louisiana
 for life.

 ``What kind of a government is this where they negotiate with my mother, tell her
 one thing and turn around and do the complete opposite?'' asked Miguel Villar,
 older brother of the inmate, who described his mother as devastated by the
 development.

 A KEY ROLE

 Sheriff Fuselier said the mother's role was instrumental in ending the six-day
 standoff. The prisoners gave up a few hours after she arrived in St. Martinsville
 with her son's former girlfriend.

 ``This is no trap . . .,'' she said. ``You're going to Cuba.''

 Her eldest son, who runs a Miami muffler shop, accused federal officials of using
 his mother, and said they never explained why they reneged.

 ``Where are they? They don't call and say anything. None of them,'' Miguel Villar
 said. ``They got her help and they got the stuff resolved peacefully and they
 disappear.''

 Villar Grana was the only prisoner involved in the uprising who had not completed
 his latest criminal sentence. The others were INS detainees, being held
 indefinitely because Cuba had refused to take them.

 The Justice Department gave The Herald an unedited copy of the letter that
 resolved the Louisiana standoff.

 THE LETTER

 It was dated Dec. 17, the day before Villar Grana's mother arrived to convince her
 son and the other hostage-takers that the deal was real. The mother and her
 son's former girlfriend, Maggie Garcia, said FBI agents told them the deal had
 been offered earlier, but the prisoners didn't trust it.

 It is unsigned, but has at the bottom the name David Venturella, the Immigration
 and Naturalization Service's assistant commissioner for detention and removal.
 INS is part of the Justice Department.

 ``At the present time,'' the letter says, ``the government of Cuba has agreed to
 accept the following Cuban nationals . . . '' It then lists the names of seven
 Cubans, including two who had surrendered earlier, along with their immigration
 service a-file numbers.

 The last name on the list is Roberto Villar Grana, whose file name is given as A#
 24658726.

 The letter then says, ``For this agreement to be binding, all instructions given by
 the Federal Bureau of Investigations [sic] must be followed to ensure the safe
 passage for each of you and the safe release of:''

 HOSTAGES LISTED

 It then lists the seven hostages held by the prisoners: Jail Warden Todd Louvierre,
 deputy Jolie Sonnier, and inmates Jessica Harman, Cora Perrodin, Rebecca
 Richard, Barbara Thomas and Shirley Williams.

 Sheriff Fuselier said by telephone Thursday that he was tired of answering
 questions about what transpired.

 ``I need to put this behind us. It's not that I'm being ugly about it. It's time for us to
 go back and get our things back to normal, if we ever do that. Let me tell you this:
 I never called Washington -- the sheriff of St. Martin's Parish did not call anyone
 and tell them to take anyone off the plane.''

 He refused to say if he knew who ordered the man removed from the plane.

 FBI officials have said they would not discuss the negotiations, in keeping with
 bureau policy. But New Orleans Special Agent Charles Mathews III said this
 week, ``We always negotiate in good faith.''

 In Washington, INS chief spokeswoman Maria Cardona said authorities did not
 mislead the mother.

 ``It was certainly not the intention to misrepresent anything,'' she said.
 ``Unfortunately, circumstances arose later that led to his being taken off the
 plane.''

 She added that the FBI was investigating all of the circumstances surrounding the
 rape allegation.