The Obama administration Monday lifted a veil of secrecy surrounding the status of the detainees at Guantánamo, for the first time publicly naming the four dozen captives it defined as indefinite detainees — men too dangerous to transfer but who cannot be tried in a court of law.

The names had been a closely guarded secret since a multi-agency task force sifted through the files of the Guantánamo detainees in 2009 trying to achieve President Barack Obama’s executive order to close the detention center. In January 2010, the task force revealed that it classified 48 Guantánamo captives as too dangerous to transfer but ineligible for trial because of a lack of evidence, or because the evidence was too tainted.