By Elise Labott
The State Department will soon designate a militia led by a former Guantanamo Bay detainee as a terrorist group and connect it to the deadly 2012 Benghazi attack, U.S. officials familiar with the decision told CNN.
Officials said militants under the command Sufian bin Qumu took part in the armed assault on the U.S. diplomatic compound that killed Ambassador Chris Stevens and three other Americans.
Qumu is the leader of the group Ansar al-Sharia in the eastern Libyan city of Darnah, one of several militias believed to be responsible for the attack.
The group also has branches in Benghazi and Libya. Officials said the State Department is expected to designate all three branches as foreign terrorist organizations in coming days.Themove allows the United States to freeze assets, impose travel bans on their members and affiliates, and prohibit Americans from offering material support.
Qumu apparently has a long history with al Qaeda.
He was a central figure at an Osama bin Laden terror training camp in Afghanistan in the 1990s before moving to Sudan to work as a driver for one of bin Laden's companies.
He fought alongside the Taliban battling American forces after the 2001 invasion of Afghanistan, before being picked up in Pakistan and sent to Guantanamo.
He was released to Libyan custody in 2007 and in 2008 was set free by Libyan authorities.
In an interview with a local media outlet in 2012, Qumu made clear that the time he spent in U.S. custody left him embittered toward the United States. But he denied he was a supporter of violence.
Libyan sources have told CNN in late 2012 that the investigation indicated the perpetrators of the attack came from beyond the Benghazi area, possibly Derna, and slipped away immediately after the assault.
American officials confirmed that witnesses place men under Qumu's command before the Benghazi attack, but it's unclear if they were part of a planned assault.
The Obama administration maintains that intelligence suggests the siege was an opportunistic attack that did not involve significant planning. Darnah is several hours drive from Benghazi.
The State Department also plans to identify Qumu and two militia leaders as "specially designated global terrorists," which offers the United States other tools to freeze their financial assets and bar American citizens and companies from doing business with them.
According to the officials, the two individuals are Ahmed Abu Khattala and Seif Allah bin Hassine. Kattala was one of several suspects named in an August federal criminal complaint in the attack.
Khattala, a prominent member of Ansar al-Sharia in Benghazi , had openly operated in Benghazi for months, flaunting U.S. authorities who have been unable to investigate the attack or question any suspects because of the lawless security situation in Eastern Libya.
In October, U.S. officials scrapped a plan to capture Khattala in Benghazi for fear that such a move could trigger unrest and cause the collapse of the Libyan government.
In an interview last year with CNN's Arwa Damon, Kattalah acknowledged being at the U.S. compound in Benghazi during the attack, but denied being involved in the violence.
The United States has said Tunisia branch of Ansar al-Sharia was responsible for the Benghazi attack and another against an American school in Tunis. It also has been implicated in attacks against Tunisia security forces, assassinations of Tunisian political figures and attempted suicide bombings of tourist locations.
- CNN Terrorism Analyst Paul Cruickshank contributed to this story.