In exchange for the release of U.S. Army Sgt. Bowe Bergdahl, the U.S. agreed to free five Taliban commanders from the military detention center at Guantanamo Bay, Cuba. They were among the Taliban’s most influential commanders. (Tom LeGro and Natalie Jennings/The Washington Post)

The release of five senior Taliban figures in exchange for the only U.S. soldier in captivity has put the spotlight on a controversial and much-debated aspect of the 12-year-old war against terrorism: How many of the detainees transferred out of the military prison at Guantanamo Bay, Cuba, have returned to the fight?

About 614 detainees held at the detention center since it opened in 2002 have been sent home or resettled in third countries by the George W. Bush and Obama administrations, according to the most recent version of a biannual report published by the Office of the Director of National Intelligence and required by Congress. Of those, 104 — about 16.9 percent — are confirmed to have returned to terrorist activity of some kind, the report says. An additional 74 former detainees — 12.1 percent — are suspected of engaging in terrorist activities after their release, defense officials say.

The military says it uses fingerprints, DNA analysis and “well-collaborated intelligence reporting” to verify who has rejoined al-Qaeda and other terrorist organizations, the office said in a fact sheet published in 2009.

The detainee statistics released by the Pentagon have been challenged. In particular, a project conducted at Seton Hall University suggested that evidence against former detainees listed in the “suspected” category was sometimes flimsy. Seton Hall also highlighted a number of past detainees who were released from Guantanamo Bay and started careers as diplomats, businessmen and in other civilian jobs.

The issue of tracking former prisoners has become current again as analysts assess the background of the five detainees released in exchange for Army Sgt. Bowe Bergdahl, who was freed Saturday in an elaborate swap with the Taliban. The sergeant, who is said to have been captured after walking away from his base in Paktika province in Afghanistan in 2009, was exchanged for five men who are considered by some critics of the deal to be at high risk of becoming involved in additional attacks against the United States and its allies.

“I am eager to learn what precise steps are being taken to ensure that these vicious and violent Taliban extremists never return to the fight against the United States and our partners or engage in any activities that can threaten the prospects for peace and security in Afghanistan,” said Sen. John McCain (R-Ariz.).

The five former detainees include Khirullah Said Wali Khairkhwa, who was associated directly with Osama bin Laden and Mohammad Omar, the Taliban’s supreme commander, according to a March 2008 assessment by defense officials at Guantanamo Bay that was later released by the anti-secrecy group WikiLeaks. After the attacks of Sept. 11, 2001, Khairkhwa represented the Taliban in meetings with Iranian officials who were interested in “supporting hostilities against U.S. and Coalition forces,” the assessment said.