American officials suspect a former Guantanamo Bay detainee of leading the attack on the consulate in Benghazi, the Washington Post's Adam Goldman is reporting.

Abu Sufian bin Qumu, who was a prisoner from 2002 until 2007, is now the leader of the Darnah, Libya, branch of Ansar al-Sharia. Witnesses have told officials that Qumu's men were in Benghazi before the September 11, 2012 attack that killed four, though, WaPo says, "It's unclear if they were there as part of a planned attack or out of happenstance." The New York Times reported last month that Ansar al-Sharia was linked to the Benghazi attack. Whether or not Ansar al-Sharia is linked to al-Qaeda is a source of some debate.

Qumu, according to his Guantanamo prisoner file, was a "probable member of al-Qaeda," "an associate of UBL's [Osama bin Laden's]" and "likely to pose a threat to the US, its interests and its allies." He escaped a Libyan prison in 1993 and was captured by the United States in Pakistan. He was transferred to Libya in September 2007 "for continued detention," but the Libyan government released him in 2008.

While WaPo's story came out today, this isn't exactly new news. In 2012, Fox News' Bret Baier reported that bin Qumu "was likely involved in the attack." And last October, Fox News again reported that a source said bin Qumu was in Benghazi the night of September 11, 2012, adding that ambassador Chris Stevens, who was killed in the attack, visited Libyan prisons to check on the welfare of former Guantanamo detainees during the time bin Qumu was being held by Libyan authorities.

According to WaPo, the Darnah, Benghazi and Tunisia branches of Ansar al-Sharia will soon be designated "foreign terrorist organizations," and bin Qumu a "specially designated global terrorist."