Air Force Lt. Gen. Randall M. Schmidt takes over for Brig. Gen. John Furlow, according to the U.S. Southern Command in Miami, which oversees the camp in eastern Cuba.
The move would allow Schmidt to question Maj. Gen. Geoffrey D. Miller, a two-star general who commanded the camp during many of the incidents detailed in recently released FBI memos that complain of "aggressive" interrogation techniques. Miller was in Guantanamo from October 2002 to March 2004 and was sent there to get more information from terror suspects.
U.S. military regulations require that an investigating officer must outrank anyone who is interviewed. Furlow requested that a more senior officer be appointed.
"I don't know who will be questioned, but this allows Schmidt to question a two-star general," Col. David McWilliams, a spokesman for Southern Command, said Monday.
Gen. Bantz J. Craddock, Southern Command's commander, has given until March 31 to complete the investigation.
The military maintains that most incidents detailed in the FBI memos occurred in 2002 when the prison was just opening, and that some of the interrogation techniques labeled as "aggressive" are no longer in use.
Documents published in December show FBI agents warned the government about abuse and mistreatment shortly after the first prisoners arrived in early 2002, more than a year before a scandal at Iraq's Abu Ghraib prison. One letter, written by a senior Justice Department official and obtained by The Associated Press, suggested the Pentagon failed to act on the FBI complaints.
The American Civil Liberties Union released similar e-mails obtained under the Freedom of Information Act in which FBI agents accused interrogators of inserting lit cigarettes in prisoners' ears and shackling them for hours, forcing them to soil themselves.
Craddock opened an investigation in December after the release of the FBI documents. Some 70 people have been interviewed, officials said, and extensions have been given to allow for more potential witnesses to be interviewed.
Some 550 prisoners are being held at Guantanamo Bay, many for more than three years without charge or access to attorneys.
By Frank Griffiths