"We know that this is a firm signal around the globe that as our government is still wading through a standstill right now, that we are still vigilant as a country and focused on international terror, and we're not going to step down at all," Bartley told CNN's "New Day Sunday."
Bartley said while she was relieved when Osama bin Laden -- also indicted in the embassy attacks -- was killed in 2011, she's also happy that al Libi was taken into custody.
"Certainly, we are very pleased to know that we can have someone who is captured, and for the wealth of information that may be available to our intelligence community and our military personnel," she said. "You can't put a price on that."
CNN's Nic Robertson, a veteran of covering al Qaeda, said al Libi's arrest is a "huge deal."
"He's a big player in al Qaeda (and) in one of the key target areas, in the north of Africa," he said. "This is a significant step."
Stops in Afghanistan, Britain, Iran and beyond
The FBI's page on al Libi -- part of its roster of "Most Wanted Terrorists" and noting the $5 million reward being offered for information leading directly to his apprehension -- says that he is accused in a "conspiracy to kill United States nationals, to murder, to destroy buildings and property of the United States, and to destroy the national defense utilities of the United States."
Born Nazih Abd al Hamid al Ruqhay, al Libi joined al Qaeda soon after its founding, as the terrorist organization built up its presence in Afghanistan and Pakistan.
When the group's late leader Osama bin Laden relocated to Khartoum, Sudan, in 1992, al Libi went with him.
As the 1990s continued, al Libi came to be known as one of al Qaeda's most capable operatives, especially for his expertise in surveillance and computers.
A fellow al Qaeda operative at one point testified that al Libi was in Nairobi in 1993, allegedly checking out possible targets, including the U.S. Embassy.
The blast in Kenya's capital five years later ended up killing more than 200 people and wounding 5,000. The Tanzania blast went off nearly simultaneously, leaving 11 people dead.
His wife denied that he had any role in any bombing and said that after he returned to Libya in 2011 during the revolution, he had been asking the Libyan government to help him clear his name. She did admit that he had belonged to al Qaeda, but said he was a personal guard for bin Laden until he left the terror group in 1996.
Al Libi at one point joined the jihadist Libyan Islamic Fighters Group before moving to Qatar and then Britain, settling in Manchester.
It was there, in 2000, that police raided his home.
Authorities uncovered a document that became known as the "Manchester Manual" -- hundreds of pages of guidance on carrying out a terrorist campaign. Among them: a document that called for "attacking, blasting and destroying" embassies.
But what they didn't find was al Libi, who had left the country before the raid.
He is thought to have spent time subsequently in Afghanistan before fleeing to Iran after the fall of the Taliban. Western intelligence sources believe he remained in that country before going home to Libya.
After years in native Libya, al Libi in U.S. hands
In September 2012, CNN was first to report that al Libi was alive and well in Libya. Western intelligence had tracked his movements in Tripoli, and had even taken surveillance photos.
Western intelligence sources said that there was concern that al Libi was working to establish an al Qaeda network in the North African nation, but no evidence has since materialized that he continued to be involved in terrorist operations after he returned to Libya.
So how long had he been home?
In December 2010, before the outbreak of the unrest that ended with Moammar Gadhafi's death, Libyan authorities told a United Nations committee that al Libi had returned, even giving a Tripoli address for him.
And one Western intelligence source said al Libi appears to have been in Libya in the spring of 2011, when the civil war was in full swing.
Family members told CNN al-Libi returned to Tripoli in 2011 to take part in the revolution against Gadhafi. His wife, four sons and daughter had arrived from Iran the previous year.