Agents from the U.S. Federal Bureau of Investigation describe the abuse in newly-released e-mails obtained by the American Civil Liberties Union.
In one e-mail, an FBI agent says he saw Guantanamo prisoners chained to the floor for up to 24 hours and left to defacate on themselves.
In another, the FBI reports that an unnamed individual saw Iraqi civilian detainees being beaten and strangled.
The e-mails also allege that Guantanamo military interrogators posed as FBI agents to avoid accountability for their deeds.The White House has denied one allegation in the e-mail that President Bush signed an executive order approving certain interrogation techniques. Some information for this report provided by AP and Reuters.