Luis Posada Carriles' defense attorneys claim that government prosecutors put a covert counter-intelligence agent of the Cuban government on the witness stand and have delayed handing over documents regarding his identity.
Now the federal judge presiding over the high-profile and politically charged perjury case against the 83-year-old Cuba native and former CIA agent will decide if the case can continue.
U.S. District Judge Kathleen Cardone was expected to rule Tuesday on the request for a mistrial from attorneys for Posada Carriles. It's the fifth such defense request since the trial began Jan. 10.
Prosecutors allege Posada lied while seeking U.S. citizenship during immigration hearings in El Paso, making false statements about how he sneaked into the U.S. in March 2005, and failing to acknowledge planning a series of 1997 bombings in Cuba that killed an Italian tourist.
Posada Carriles, who spent decades as a Washington-backed Cold Warrior, traversing Latin America to foment violence, is Public Enemy No. 1 in Cuba. He admitted responsibility for the bombings of hotels and the Cuban beach resort of Varadero during a 1998 interview with The New York times, but has since recanted.
Cuba and Venezuela would like to try Posada Carriles for the 1997 bombings or the 1976 bombing of a Cuban airliner that killed 73 people, but a U.S. immigration judge has previously ruled he can't be sent to either country for fear he could be tortured.
In the U.S., Posada Carriles is not on trial for the bombings. Instead, he faces perjury, obstruction and immigration fraud charges.
Defense attorneys have taken issue with the testimony of Lt. Col. Roberto Hernández Caballero, who described the 1997 bombings of hotels in Havana and the Cuban beach resort of Varadero for jurors last week.
Hernández Caballero has testified twice before in separate U.S. court proceedings, including a federal hijacking case in Tampa, Florida. He said then that he was a member of the Cuba's counter-intelligence agency. During Posada Carriles' trial, Hernández Caballero said only that he was an investigator.
Posada Carriles' defense team says it found out late about Hernández Caballero's real job description because prosecutors delayed providing the transcript of his testimony in the Florida case.
Assistant U.S. Attorney Timothy Reardon called the request for a mistrial "an extraordinary and ridiculous motion."
The defense motion also referred to two previously classified FBI reports it says prosecutors also were slow to turn over. The first asserted that the 1997 bombings were the work of the Cuban government so as to blame them on the United States, or that they were carried out by dissenting officers within the island's armed forces or Interior Ministry.
The second report warned that Posada Carriles could be the target of a 2004 assassination attempt by the Cuban government. Posada Carriles was shot in the face by would-be assassins in Guatemala in 1990.
Posada Carriles participated indirectly in the United States' failed Bay of Pigs invasion of Cuba in 1961 and later served as head of intelligence for Venezuela's government. A Venezuelan military court dismissed charges against him in the airliner bombing, but he escaped from prison before a civilian trial against him was completed.
He was arrested in Panama in 2000 in a plot to kill Castro during a summit there. He was pardoned in 2004 before turning up in the U.S.
Posada Carriles has been living in Miami since his 2007 release from an immigration detention center in El Paso.
The Associated Press contributed to this report.