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At least two of the key suspects in the Benghazi terror attack were at one point working with Al Qaeda senior leadership, sources familiar with the investigation tell Fox News.

The sources said one of the suspects was believed to be a courier for the Al Qaeda network, and the other a bodyguard in Afghanistan prior to the 2001 terror attacks.

The direct ties to the Al Qaeda senior leadership undercut early characterizations by the Obama administration that the attackers in Benghazi were isolated “extremists" -- not Al Qaeda terrorists -- with no organizational structure or affiliation.

The head of the House Intelligence Committee, Chairman Mike Rogers, R-Mich., who receives regular intelligence briefings and whose staffers continue to investigate the Benghazi terrorist attack, would not discuss specific suspects or their backgrounds.

But he said the ties to Al Qaeda senior leadership, also known as Al Qaeda core, are now established.

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    “It is accurate that of the group being targeted by the bureau, at this point, there’s strong Al Qaeda ties,”  Rogers told Fox News. "You can still be considered to have strong ties because you are in the ring of operations of Al Qaeda core. ... There are individuals that certainly fit that definition."

    Counterterrorism expert Thomas Joscelyn, a senior fellow with the Foundation for Defense of Democracies, told Fox News that investigators are finding "more and more ties -- not just to Al Qaeda's branch in North Africa ... but Al Qaeda senior leadership in Pakistan."

    A year ago, Fox News' Bret Baier was first to report that a former Guantanamo detainee, Sufian bin Qumu, was suspected of training jihadists in eastern Libya for the attack.

    Now, sources tell Fox News that Benghazi suspect Faraj al Chalabi, also a Libyan national whose ties to Usama bin Laden date back to 1998, is believed to be a former bodyguard who was with the Al Qaeda leadership in Afghanistan in 2001.

    After the Benghazi attack, al Chalabi fled to Pakistan where reports suggest he was held, then later returned to Libyan custody and eventually released. He was first publicly identified as a suspected terrorist in 1998 by the regime of former Libyan dictator Muammar Qaddafi for his alleged role in the murder of a German intelligence official, Silvan Becker and his wife. An Interpol arrest warrant in March 1998 named al Chalabi, two other Libyans and bin Laden as the likely perpetrators.

    “Our sources say al Chalabi is suspected of bringing materials from the compound to Benghazi to Al Qaeda senior leadership in Pakistan. It's not clear what those materials consisted of but he is known to have gone back to Pakistan immediately after the attack,” Joscelyn said.

    Separately, and for the first time, Rogers laid out a timeline for the attack which suggests significant advance planning. According to the congressman, there was an “aspirational phase” several months out, where the idea of an attack was thrown around, followed by “weeks” of operational planning, and then the ramp up to the Sept. 11 assault which lasted up to several days. This assessment is in stark contrast to initial administration statements that the attack was “spontaneous” and achieved with little planning.

    “I believe that they had an operational phase that lasted at least a couple of weeks, maybe even longer. And then an initiation phase that lasted a couple or three days prior to the event itself. And so this notion that they just showed up and decided this was a spontaneous act does not comport with the information at least with what we have seen in the intelligence community,” Rogers told Fox News.

    Some counterterrorism analysts concur with Roger’s assessment, describing the mortars used to strike the CIA annex in the second wave of the attack as "smoking gun" evidence -- as mortars require skill to fire, and typically must be pre-positioned to ensure accuracy. On Sept. 11, two mortars struck the CIA annex, killing former Navy SEALs Glen Doherty and Tyrone Woods.

    The opposing analysis is that the mortars were set in the early morning hours of Sept. 11, and that the terrorists did not bring equipment with them that suggests significant planning.

    Fox News contacted the FBI which is in the lead on the Benghazi investigation, as well as the CIA and the National Counterterrorism Center, or NCTC. Both the NCTC and the CIA declined to comment. There was no immediate response from the FBI.