U.S. special operations forces were ready, if ordered, to enter Benghazi and capture Ahmed Abu Khattalah, a leading figure in the Ansar Al-Sharia militia. But the mission never materialized.
The United States believes Ansar Al-Sharia was behind the September 2012 armed assault on the U.S. diplomatic mission that killed Ambassador Christopher Stevens and three other Americans.
President Barack Obama has openly said it is a "priority" to bring the Benghazi suspects "to justice." The FBI continues to investigate the attack and Khattalah is under federal indictment, CNN's Evan Perez has reported.
The FBI has also published photographs of people seen at the compound on the night of the raid that it wants to talk to.
U.S. intelligence agencies and military special operations forces have moved in and out of Libya for several months with the permission of the Libyan government. They are looking for opportunities to capture alleged suspects in the Benghazi attack, developing a list of nearly a dozen individuals.
But earlier this month may have been one of the closest times they have come to being able to conduct a mission, officials say.
Khattalah had openly operated in Benghazi for months and even has been interviewed by CNN's Arwa Damon.
But it was this month that U.S. intelligence finally had enough information about his specific whereabouts that a raid seemed feasible to military planners, several U.S. officials tell CNN.
All of the officials declined to be identified because of the sensitive nature of the information.
The Benghazi attack has become a political flashpoint between Republicans in Congress and the Obama administration over its handling of security at the compound and the slow-to-evolve explanation of what occurred.
A top critic, Sen. Lindsey Graham, applied new pressure this week when the South Carolina Republican said he would would block all Obama administration nominees before the Senate until survivors of the assault testify before Congress.
Top level meeting
Abu Anas al-Libi, accused of playing a role in the 1998 U.S. Embassy bombings in Kenya and Tanzania, was grabbed on October 5 in a daylight raid outside his home. The Khattalah mission might have been ready to go as soon as the next day, according to some officials.
A top level White House meeting was scheduled to get the final signoff from Obama, around October 7, officials told CNN.
But the mission never materialized, partly because there was so much publicity inside Libya and in the western press about the al-Libi capture.
With the Libyan government dealing with public outcry about the U.S. incursion into Libya, the White House became worried any raid in Benghazi could destabilize, and potentially bring down the fragile Libyan government.
The Libyan government publicly denounced the operation following the al-Libi raid, but key Libyan government officials had given the United States permission to enter Libya and go after both al-Libi and Khattalah, according to a senior U.S. official.
The brief kidnapping of Prime Minister Ali Zeidan after al-Libi was seized underscored to U.S. officials the fragility of the Libyan government and that it likely could not withstand the political and security fallout from a second U.S. commando raid.
American officials will not discuss timing of any future operations to capture Benghazi suspects, but note Obama's policy that they will be pursued.
Concern about Libyan gov't
One reason for the U.S. effort is the Libyan government is seen as too weak to go after suspects on its own.
But the inability to get Khattalah is leading to sensitive questions inside the administration about the tradeoff between getting al-Libi and going after the perpetrators of the politically charged Benghazi attack.
Two officials have told CNN that to some extent, getting al-Libi was proof to the White House that commandos could reliably get into Libya, get to their target, and get out. Al-Libi, though wanted by the United States, was not seen as a highly risky target. He was not hiding his presence in Tripoli.
The difference is Benghazi is a virtual "no-go" zone for westerners because of the control of various militia movements there.
One official said "not enough thought" may have been put into the impact of getting al-Libi and not moving quickly to get Khattalah before a backlash emerged.
But he also noted it was always going to be "complex" to attempt two covert raids nearly simultaneously. He and other officials said it wasn't a matter of incorrectly prioritizing one target over the other, but simply going after the most readily available target first.