According to the Pentagon, as reported in Reuters,
 

one out of every seven, terrorism suspects formerly held at the U.S. detention site at Guantanamo Bay are confirmed or suspected of having returned to terrorism, the Pentagon said on Tuesday.

Among the more recent cases mentioned were two men repatriated to Saudi Arabia in 2007, Abu Sufyan al-Azdi al-Shihri and Mazin Salih Musaid al-Alawi al-Awfi, said to have announced in a video message in January that they were leaders of al Qaeda in the Arabian Peninsula, a new group.

Among those accused of the most serious offenses was Said Mohammed Alim Shah, also known as Abdullah Mahsud. Repatriated to Afghanistan in 2004, he blew himself up to avoid capture by Pakistani forces in July 2007, the summary said.

According to a Pakistani official, he directed an April 2007 suicide attack that killed 31 people, it said.

The Pentagon said it required "a preponderance of evidence" such as fingerprints, DNA or photographs, to confirm that a former detainee had been involved in terrorism.

Human rights groups have voiced skepticism about previous Defense Department statements on former Guantanamo detainees taking part in terrorism. Some have suggested they are intended to stoke fear among Americans about its closing.

(snip)

Administration officials have said harsh treatment of detainees there and the detention of suspects for years without trial have tarnished America's image and acted as a recruitment tool for terrorists.