Jan 9, 2007
Nayibe Rojas - better known by her alias, Sonia - is accused of smuggling hundreds of tonnes of cocaine into the US. She denies the charges.
Ms Rojas was a leading member of the left-wing rebel group, Revolutionary Armed Forces of Colombia (Farc).
Her trial is part of US efforts to weaken the group, which gets much of its funding through the drugs trade.
Ms Rojas, 39, was deported in March 2005, following her capture in southern Colombia.
The BBC's Jeremy McDermott, in Colombia, says US prosecutors are not only hoping to convict her as a drugs trafficker, but to paint the Farc as now nothing more than a drugs cartel.
The trial is being held in the same courtroom where another Farc commander, Rocardo Palmera, was tried last year.
He was accused of plotting to kidnap three US citizens after their plane crashed in Colombia.
A mistrial was declared in November after jurors failed to reach a unanimous verdict.
The US last year announced drug indictments against 50 Farc leaders - none of whom have so far been captured.
Farc is the largest rebel group in Colombia. It has been fighting the government for more than four decades.