BENGHAZI, Libya — The militia commander who led the deadly raid on the U.S. mission in Benghazi is an Islamist and former political prisoner whose fighters were also blamed for assassinating a senior military officer after he defected to the opposition during last year's revolution against Moammar Kadafi, a senior Libyan official said.
FBI agents have been shown a cellphone picture of the commander at the scene of the attack, according to Libyans familiar with the investigation. But it is unclear where the man, identified as Ahmed Abu Khattala, is now, and militias loyal to the government say they have received no orders to arrest him or any other suspect in connection with the attack.
In a contentious exchange with Republican presidential nominee Mitt Romney on Tuesday night, President Obama reiterated his pledge to bring the attackers to justice. But the chaos in Libya after the fall of Kadafi creates daunting obstacles.
With the army and police forces yet to be rebuilt, the government depends on a patchwork of militias to maintain security. Although many of the largest armed groups are allied with the government, authorities are reluctant to order a local militia to move against the attackers for fear of inflaming rivalries — or having their orders refused.
Sending in a militia from 400 miles away in Tripoli risks exacerbating tension between Libya's eastern and western regions. And even though Libya's weak central government is pro-American, unilateral U.S. military action would invite a backlash.
A senior Libyan official on Wednesday identified the commander in the cellphone photo taken by a witness to the attack as Abu Khattala, who founded a militia of former prisoners called the Abu Obeida brigade. That group was blamed for the assassination of Gen. Abdul Fatah Younis, Kadafi's former interior minister, who defected to the rebels and had become one of their senior military commanders.
The killing of Younis in eastern Libya in July 2011 was an indication of division within rebel ranks and a harbinger of the disarray still plaguing the country. No one was charged in his death, but Libyans speculated that Abu Khattala could have ordered it as retribution for his treatment while in Kadafi's infamous Abu Salim prison.
"He is the one who is responsible" for leading attackers on the U.S. mission, said the Libyan official, who spoke on condition of anonymity in discussing the ongoing investigation.
Some experts believe the Abu Obeida brigade is now part of Ansar al Sharia, an Islamist militia and social organization that disappeared from Benghazi after it was targeted in popular protests against the attack. U.S. officials reportedly intercepted communications from members of Ansar al Sharia bragging about the attack to Al Qaeda affiliates in North Africa.
"All of these rogue Islamist brigades swim in the same small pool" in Libya, said Frederic Wehrey, an expert at the Carnegie Endowment for International Peace in Washington.
Abu Khattala's whereabouts was unknown, but the Libyan official said he's probably 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. The official did not want to be identified because of the sensitivity of the issue.
The official's mission was attacked by militants this year, one of a number of security incidents involving foreigners across Libya. But Libyan authorities didn't investigate the attacks — and the mission didn't expect it to do so.
"They don't have the power. They depend for their own security on the brigades," the official said. "At the same time, the brigades don't want to give up their weapons because they don't trust the government."
U.S. officials also described a perfunctory investigation of an incident at the U.S. mission in Benghazi five months earlier, when a crude bomb was detonated within its walls. No one was injured, and the damage was minor.
Despite U.S. pressure to find those responsible, experts said Libyans would prefer to punish the attackers in their own time and on their own terms.
"They will be held accountable, but not in terms that Americans might expect," said Brian McQuinn, an Oxford University scholar who has spent several months in Libya researching armed groups. Tribal elders could engage in protracted negotiations to determine the fate of the suspects.
"To go in with a huge force — other brigades would be offended. They'll say, 'Who are these people coming into Benghazi?'" McQuinn said. "They have to develop legitimacy and have to be invited in."
Unilateral American military action would almost certainly cause more problems for the United States in the Islamic world. And although most new Libyan leaders are grateful to Washington for supporting the revolution that overthrew Kadafi, they issue stark warnings when asked about a U.S. strike on militant targets.
"If they do an irresponsible action, we will have to organize some action in return," said Suliman Zubi, an independent lawmaker from Benghazi. "Our government is not going to accept anything like this."
FBI agents have taken the lead in the investigation of the Sept. 11 attack that killed Ambassador J. Christopher Stevens and three other Americans. But agents couldn't get access to the compound for three weeks because of security concerns and delays in obtaining Libyan approval. The team has conducted the majority of its work in Tripoli, the capital, including interviewing several Libyans who guarded the Benghazi mission and witnessed the attack.
Libya's new prime minister, Ali Zidan, is expected to form a Cabinet by the end of the week that will include the ministers responsible for rebuilding the security forces. In the meantime, officials are eager to show they're trying to help. After White House counter-terrorism advisor John Brennan visited Tripoli last week, the Libyan government formed a committee of senior political and security officials to serve as a liaison.
"We made this decision to make it clear that we are here to help the Americans and to help ourselves," said Saleh B. Gaouda, a member of parliament from Benghazi.
The incident last spring at the Benghazi mission, however, helps illustrate how much ground needs to be covered.
On April 6, a group of Libyan guards who were supposed to be helping to secure the U.S. mission allegedly detonated a homemade bomb inside the compound, according to internal State Department emails obtained by The Times.
Several suspects were detained moments later. One was identified as Ahmed Marimi, a compound guard whose car was being driven by two other suspects who were believed to have tossed the bomb. They were identified as Ibrahim Fawzi Etwear, a former guard fired for vandalism, and Mohe El Dean Bacher, a guard who recently had been demoted.
Etwear and Bacher each gave a brief statement but were released within a week. Local officials said there was no "hard evidence" because no trace of explosives was found on the suspects.
Libyan officials did agree to issue a restraining order to keep the suspects away from the compound. And they decided to prosecute a security official who fired a warning shot to make the suspects stop.
Bengali reported from Benghazi and Serrano from Washington.