Since 2006, more than a dozen of Colombia's most notorious paramilitary leaders have been extradited to the United States to face drug-trafficking charges....

The extraditions stunned Colombians, who had hoped that testimony from the men, given as part of a national amnesty program, would help expose the truth about two decades of vicious murders, assaults and kidnappings....

But outrage over the extraditions reached a boiling point earlier this year, when U.S. District Judge Reggie Walton blocked public access to seven of the paramilitary leaders' cases, erasing virtually every trace of their existence.