Three Americans went on trial in Kabul this week on charges that they operated an illegal private prison as part of their freelance search for terrorists. The three menJack Idema, Edward Caraballo, and Brent Bennettare charged with robbing, beating, and torturing Afghan detainees. At the opening hearing, Idema claimed he was part of a secret Pentagon-approved counterterrorist unit and had been working with Afghan and U.S. officials. He said he had captured several Taliban and al Qaida members and turned them over to U.S. forces. Bin Laden has half a million dollars on my head, he told a reporter. U.S. and Afghan officials denied any knowledge of Idema. Caraballo said he was a journalist reporting on Idemas work, while Bennett did not speak.