Ansar al-Sharia, the hardline Islamist faction whose fighters are accused of taking part in the deadly attack on the U.S. consulate in Benghazi last week, has been a visible presence on the streets of the city that birthed Libya's revolution for months now. Sporting the long beards and cropped mustaches usually associated with the ultra-conservative Salafist strain of Islam, its members drive around Benghazi in vehicles emblazoned with the group's distinctive insignia: two raised Kalashnikovs surrounding a clenched fist with raised forefinger above an open Quran.

The logo also features prominently at the entrance to Ansar al-Sharia's base, a former regime security compound in the center of Benghazi seized by the brigade. Most Benghazi residents eye the heavily armed men who come and go from the base warily. Many fear their uncompromising ideology, which holds democracy to be un-Islamic. Some blame them for a string of attacks, including the desecration of British World War II graves, and attempts to destroy Sufi shrines in the area. Security officials complain Ansar al-Sharia has rejected efforts to integrate its fighters into Libya's nascent government forces.

In the wake of the attack that claimed the lives of U.S. Ambassador Christopher Stevens and three other Americans last Tuesday night, there are signs that Ansar al-Sharia may have worn out its welcome in Benghazi.It is clear that the Islamist group feels under pressure: Several Libyan officials, including Mohammed Magariaf, president of the country's recently elected National Congress, have suggested the assailants included heavily armed men drawn from Ansar al-Sharia's ranks who had been in contact with al Qaeda in the Islamic Maghreb.

Two members of Ansar al-Sharia's eight-man leadership council -- Mohammed al-Zahawi, considered the brigade's overall leader, and Sheikh Nasser al-Tarshani, who heads its religious committee -- agreed to a telephone interview just hours before they met with the Libyan Army chief of staff, Gen. Yusuf Mangoush, on the night of Sept. 17.

For supposedly radical Islamists, the two leaders have surprisingly mundane day jobs. Zahawi is a 39-year-old Benghazi native who runs a shop selling electrical appliances, while Tarshani, 38, works in construction. What both men, and many others in Ansar al-Sharia, have in common is the shared experience of incarceration in Abu Salim, the notorious Tripoli prison where political dissidents, most of them Islamists, ended up during Muammar al-Qaddafi's rule. Zahawi spent eight years in Abu Salim, while Tarshani was imprisoned for five. Neither man was a member of an established Islamist group when they were jailed, but the bonds they and others forged within Abu Salim run like a thread through Ansar al-Sharia today.

According to Zahawi and Tarshani, Ansar al-Sharia is not an al Qaeda-linked jihadist outfit, but a Benghazi-based katiba, or brigade. They say it was founded earlier this year, and comprises some 250 men. "Our members fought on the front lines during last year's war. At the time they were members of different brigades, including the February 17 brigade," said Zahawi, referring to Benghazi's most prominent fighting force. "A group of us decided to come together to establish a separate brigade under the name Ansar al-Sharia with the goal of supporting sharia [Islamic law] as the frame of reference in Libya."

Zahawi and Tarshani claimed that none of the brigade's members were involved in the consulate attack, and none were among the 50 people Libyan officials say have been arrested in connection with the attack. They justified the assault, during which rocket-propelled grenades were fired into the compound and the mission set ablaze, as an "emotional" response to an Internet film that denigrated Islam and the prophet Muhammad -- but they said they disagreed with this action.

"We don't see this kind of attack as a solution for the problem. It was wrong. The killing of the ambassador was not intentional -- he died as a result of suffocation. It appears people did not even know he was inside the consulate at that time," said Tarshani.

The two leaders painted the accusation made against Ansar al-Sharia as politically motivated. "If anybody says that some of our followers have taken part, we request that they bring forward proof," Tarshani said. "Those who are accusing us and blaming us are our opponents from the secularists who do not want to see Ansar al-Sharia active in Benghazi.

Witnesses who have accused Ansar al-Sharia of involvement say some of the assailants carried a black flag with an Islamic inscription, which is also used by the brigade. "This flag is not just ours. Many people, including other brigades, use this flag," said Tarshani. "This cannot count as proof that we were there."

Zahawi and Tarshani also rejected Magariaf's reported comments regarding U.S. officials intercepting communications between Ansar al-Sharia and al Qaeda's North African franchise.

"This is not true. We challenge anyone who claims that to prove it in reality," said Zahawi. "[Magariaf] is entitled to his opinion but what is needed from him is proof for what he has said."

The Ansar al-Sharia leaders said they had no information about who might have been behind the attack but they pointed a finger at remnants of the Qaddafi regime. "We cannot exclude the hand of the Qaddafi loyalists in it. Everything is possible in this case," said Zahawi.

The Benghazi-based brigade is not the only outfit in eastern Libya to use the name Ansar al-Sharia. Another is based in Derna, a town 156 miles east of Benghazi that has a long history of Islamist opposition to Qaddafi. More than 50 of Derna's young men went to Iraq with the aim of becoming suicide bombers, the largest number from any city outside Iraq, according to a study by the Combating Terrorism Center at West Point. However, Tarshani and Zahawi denied that their group had any connection with the group in Derna, or any of its most infamous figures.

Ansar al-Sharia in Derna counts among its senior members former Guantanamo Bay detainee Sufian bin Qumu, who led a band of rebel fighters during last year's revolution. In an April interview, bin Qumu griped that he and his men had not been invited to join the army or the police.

"They did not even give me or any of my men a reward for fighting," he said.

Asked if they have any connection with Sufian bin Qumu, Tarshani replied: "No, nothing at all. That is a different Ansar al-Sharia. We share a common name but not action."

Zahawi and Tarshani reject the suggestion that, even before last week's attack, Benghazi's Ansar al-Sharia was not welcomed by most people there. Events in the city this summer cast doubt on this claim: In June, the brigade led a parade of pickup trucks loaded with heavy weaponry along the city's seafront, calling for the immediate implementation of sharia law. The rally, which also included fighters from towns such as Derna, was met with a counter-demonstration by locals, some of whom blasted rap music and threw stones.

"We all want sharia but they are sending out a message that this will be sharia through the barrel of a gun," one Benghazi Islamist sighed to me at the time. "This is hardly a way to persuade people."

Several mainstream Islamists, including members of the Muslim Brotherhood, told me they believe Ansar al-Sharia's ostentatious display that day helped contribute to the poor performance of Islamist parties in July's National Congress elections. In the days leading up to the ballot, Zahawi gave an interview on local TV declaring elections were contrary to Islam.