A retiring Marine testifying on Capitol Hill on Wednesday is likely to be a key witness in the House probe of the Benghazi, Libya, terrorist attack, an aide said.
Col. George Bristol, expected to testify behind closed doors before a House Armed Services subcommittee, was a special operations task force commander in the U.S. Africa Command, an elite unit that conducts special operations across northern Africa.
He was therefore in a position to know what options the United States had to protect Americans under attack at the U.S. diplomatic compound the night of Sept. 11, 2012, Marine Corps Times reported.
That attack by armed Islamic militants killed four Americans, including U.S. Ambassador J. Christopher Stevens. Ten others were injured.
Republicans argue the United States wasn't prepared to respond adequately to the attack. They accuse the Obama administration of downplaying or covering up the administration's handling of the attack, its lead-up and aftermath during the heat of the 2012 presidential campaign.
"Colonel Bristol has experience that could be valuable in deepening our understanding of the events of that day," a committee source told The Hill.
"Of particular interest to the committee is what our posture was in the weeks and months that preceded the attack," the source said.
Bristol, a seasoned combat commander, stepped down from his task force commander post in March.
When House Subcommittee on National Security Chairman Jason Chaffetz, R-Utah, and Senate Armed Services Committee member Lindsey Graham, R-S.C. -- two vocal critics of the administration's Benghazi response -- requested Bristol appear, they were told 3 1/2 weeks ago he retired July 1 and could not be ordered to testify.
But Marine Corps Times reported July 17 Bristol had not yet retired and was still on active duty until the end of July.
Marine Corps spokeswoman Maj. Shawn Haney confirmed Bristol would in fact retire Aug. 1.
A Pentagon spokesman said the "initial confusion" over Bristol's status was due to a "personnel administrative error."
Bristol is expected to spend his last day of service testifying before the Armed Services Committee's Oversight and Investigations subcommittee, led by Rep. Martha Roby, R-Ala.
"The Department of Defense has fully cooperated with congressional requests to understand the attacks on the Benghazi compound," Pentagon spokesman Maj. Robert Firman said, adding Bristol would "be available to meet with House and Senate members and their staffs."
CBS News reported Tuesday Bristol already met with Graham.
Congress plans more Benghazi-related hearings after its August recess.