Luis Posada Carriles, a personal nemesis of Fidel Castro, is charged with perjury and accused of lying to federal officials during his immigration hearings in El Paso.
On Tuesday, his attorney made - and was denied - his fourth request for a mistrial after repeated exchanges with prosecution witness Gilberto Abascal, who began testifying last week.
Jurors weren't present when defense attorney Arturo Hernandez called Abascal "a scoundrel" and accused him of biasing the jury by accusing Posada's lawyers of criminal wrongdoing.
Prosecutors responded that Hernandez was unfairly "injecting himself into the case."
The 82-year-old Posada also is accused of obstruction and immigration fraud.