To the untrained eye, the August 2003 letter that seemed to bear the signature of Sen. Bob Graham (D-Fla.) must have appeared impressive.

But upon closer examination, the telltale signs that the letter was a forgery were all there: The broken Spanish. The botched letterhead. And the Senator’s fantastic promise that his office and other government agencies were doing everything possible to help Roberto Martin recover the $25.5 billion he had supposedly stolen from Cuban leader Fidel Castro.

The fake letter is now just one piece of evidence in a pending criminal prosecution of Martin, an ex-felon who has been charged with conspiracy, mail fraud and impersonating a CIA agent. He is currently awaiting trial in U.S. District Court for the Southern District of Florida.

The charges stem from an elaborate scheme that the 35-year-old Miami man allegedly concocted to bilk others looking to make a quick buck, according to court documents filed by federal prosecutors. The government claims that the victims cumulatively lost in excess of $100,000.

Martin has pleaded not guilty.

The Florida Democrat’s office, meanwhile, was drawn into the case by federal prosecutors in the Sunshine State who are looking for a staff member to identify the letter purportedly signed by Graham as a fake.

While Graham’s office declined this week to comment on the pending criminal matter, court documents provide insight into the oddities of the case, which is scheduled to go to trial in early November.

According to a grand jury indictment filed in February, Martin — also known as Roberto Martin Cabrera — began falsely telling others in late 2002 that he was “working with the Central Intelligence Agency on a ‘secret operation’” that involved obtaining money he had helped steal from Castro while previously working as a spy for the Cuban government.

Martin enlisted their financial help, promising a huge windfall if they would finance the “secret operation,” which he claimed involved getting the money transferred from a Swiss bank account into several investment accounts in the United States.

It wasn’t the first time that Martin claimed to be a secret agent working for Castro.

In 1996, Martin — who had escaped Cuba on a raft two years earlier — made headlines when he told the Cuban American National Foundation, an influential group of anti-Castro Cuban exiles, that he had been recruited as part of a Cuban government plot to assassinate the group’s leaders by blowing up CANF’s Miami office.

His allegations provoked an uproar, with The Miami Herald demanding a thorough FBI probe of Martin’s claims. The FBI did probe the case, but found nothing to corroborate Martin’s information.

Several months later, Martin made headlines again when he was arrested, and later convicted, on fraud and theft charges related to a jewelry investment scheme that conned about 20 fellow Cuban exiles out of a total of about $20,000.

In the case that involved Graham’s office, the government alleges that Martin took more than $100,000 from at least one unwitting participant in the scheme and promised some investors millions in return.

A co-conspirator named Christopher Johnson — who has since pleaded guilty to one count of impersonation of an officer of the United States — said that he helped as Martin allegedly promised these individuals that they would receive hundreds of thousands of dollars, if not millions, if they would help.

To perpetuate the ruse, Martin would display a semi-automatic pistol in a holster and flash a “law enforcement-style badge” to give the impression that he was indeed working for the CIA. Johnson also carried a firearm, wore an earpiece-style radio and flashed business cards of a Miami-based Secret Service agent he was impersonating.

If that wasn’t enough to authenticate the “secret operation,” Martin also offered his marks an impressive array of “documents on letterhead appearing to be from the National Security Council, the CIA and even the White House,” according to an affidavit filed by the former Secret Service agent who investigated the case.

In one such fake letter, rife with misspellings and grammatical errors, Graham purportedly assures Martin that “all your bank operations and financial transactions of your accounts are being supervised and monitored by my office.”

“With regards to the accounts authorized by Presidential decree and protected by subtitle B-Bank Secrecy Act Amendments and related improvements, your accounts are protected by the sec. 358 sec. 360,” the falsified document states, with incorrect syntax intact. “The funds are actually (presently) at SMITH BARNEY $ 25 billion USD, BROOKSTREET $ 500 million USD, WACHOVIA $50 million USD.”

Other alleged documents turned over to prosecutors included a fake memorandum from White House Chief of Staff Andrew Card and National Security Adviser Condoleezza Rice, who is misidentified as “Counselor of the National Security” and whose first name is misspelled “Condeleza.”

Despite his claims, Martin’s four investors — including one who provided Martin with a Mercedes Benz, a Rolex watch and more than $100,000 in cash — never saw a dime, according to court documents filed by prosecutors.

A Graham spokesman declined to comment on the case, referring a reporter to a recently passed Senate resolution that authorizes the Senate Legal Counsel to represent Graham’s staff in the case.

“The defendant’s trial is scheduled to commence on or about November 1, 2004,” Senate Majority Leader Bill Frist (R-Tenn.) said in a floor statement prior to the passage of the resolution. “The prosecution has requested testimony and the production of documents from a member of the Senator’s staff who has evidence relevant to the charged offenses. Senator Graham wishes to cooperate with the prosecution’s request.”

If convicted, Martin faces a maximum penalty of up to 38 years in prison.