Libyan authorities have identified Ahmed Abu Khattala, a leader of the Benghazi-based Islamist group Ansar al-Shariah, as a leader of the attack that killed American Ambassador Chris Stevens, Libyans involved in the investigation said Wednesday.

Witnesses to the Sept. 11 attack on the American Mission in Benghazi have told The New York Times  they saw Abu Khattala leading the assault, and his role is the latest link between the attack and the Ansar, a puritanical group that wants Islamic law in Libya.

Another Libyan official told the Los Angeles Times that Abu Khattala is a former political prisoner whose fighters assassinated a senior general last year after he defected to the opposition during last year's revolution against Moammar Gadhafi.

The identity and motivation of the assailants have become a point of debate in the U.S. presidential campaign. Republicans have sought to tie the attack to al Qaeda to counter President Barack Obama’s assertion that by killing Osama bin Laden and other leaders his administration had crippled the group. Abu Khattala and Ansar al-Shariah share al Qaeda’s ideology, but operate independently and focus on Libya rather than on a global jihad against the West, the New York Times reports.

Abu Khattala’s exact role in the incident is not yet clear, and remains at large and has not yet been questioned. Militias loyal to the weak new central government say they have received no orders to arrest him or any other suspect in the Benghazi attack.

Asked last week about Abu Khattala’s role, an American in the separate U.S. investigation indicated that the United States was tracking him but cautioned that the leadership of the attack might have been broader than a single man.

A Libyan official said he probably is still in Benghazi — where his poor Laythi neighborhood has earned the moniker "Little Kandahar" — or elsewhere in eastern Libya.

"It's not whether they want to bring them to justice, but whether they can," an international official in Libya said of the government.