On the eve of an infamous presentation Anwar al-Awlaki gave at the Pentagon in 2002, the Al Qaeda operative was busy preparing -- with a prostitute he paid $400 for at a Washington hotel.

It was one of more than a half-dozen liaisons Awlaki had with prostitutes between late 2001 and early 2002, while he was under FBI surveillance, according to documents obtained by Judicial Watch and reviewed exclusively by Fox News.

The documents shed new light on the double life the American-born Awlaki was leading, while living in the Washington area and working as an imam at a mosque in Falls Church, Va.

In the years before he became publicly associated with Al Qaeda and was targeted for death by the U.S. government, Awlaki was by turns welcomed and investigated by different arms of the government -- not just over his radical ties, but his predilection for prostitutes.

Yet there is no indication he was ever brought up on charges, leading Judicial Watch President Tom Fitton to question why the cleric seemed to have a "protected status."

One document obtained by Judicial Watch, a conservative watchdog group, was a June 2002 memo from FBI Assistant Director Pasquale D'Amuro detailing Awlaki's encounters with prostitutes in the D.C. area. The memo appeared to propose charges against him, claiming he spent $2,320 on seven different occasions between Nov. 5, 2001, and Feb. 4, 2002.

It described in detail an interview with the "escort" who saw him on Feb. 4, the day before he was scheduled to have lunch at the Pentagon as an invited guest.

She claimed she had a 5 p.m. appointment with him that day, and when he arrived at her room, "she looked through the 'peep' hole ... and thought to herself that he looked like Osama bin Laden."

She later identified him as Awlaki.

He paid $400 for sex, the memo said. He was described by the escort as "very polite." Awlaki, who has a record with prostitutes -- he was booked in San Diego on charges of soliciting prostitutes in the late '90s -- also told the escort that he likes to use escort services when he travels to Florida, according to the memo.

The memo described in graphic detail the services rendered for Awlaki during that period. One prostitute described a December 2001 encounter where Awlaki paid $300, in order to watch "as she engaged in erotic behavior and stimulated herself."

They met again, for the same activities, in mid-January 2002, according to the document.

Fox News was first to report in 2010 that Awlaki was invited to the Pentagon within months of the Sept. 11, 2001, attacks as part of an outreach effort with supposedly moderate Muslims.

Awlaki would later emerge as a major mouthpiece for Al Qaeda in the Arabian Peninsula, being linked to recent attacks including the Fort Hood shooting as well as the attempted Christmas Day bombing on a Detroit-bound flight.

He was the first American known to be included on the government's kill-or-capture list. He was killed in a U.S. drone strike in Yemen in September 2011.

One document obtained by Judicial Watch also depicted what was described by the group as a "computer database record" retrieved in February 2002, before his Pentagon lunch. It listed Awlaki's name and included the warning to "approach with caution," listing him under the heading of "terrorist organization member."

Fitton said the new documents raise questions about the relationship between Awlaki and the U.S. government.

"One can fairly conclude that the al-Qaeda mastermind had some type of 'protected status' with our government -- despite his terrorist and criminal activities," Fitton said. "We knew from days after the attacks on the World Trade Centers that (Awlaki) was a dangerous character, so why did it take the government ten years to bring him to justice?"

Fox News asked the FBI for comment, specifically on why Awlaki apparently was not prosecuted and whether the information on his alleged liaisons was shared with the Pentagon. The FBI has not yet commented on the documents.

Fox News' Catherine Herridge contributed to this report.