Bill Clinton's appearance earlier this month on "Jimmy Kimmel Live!" – where he was asked about his interest in UFOs – has been subjected to body-language analysis by an investigator of paranormal claims, who says the former president exhibited signs of "significant apprehension, stress and guarded behavior."

News of Clinton's inquiries, after he became president, into what information the government held on UFOs and space aliens has been widely reported.

Following the first portion of Kimmel's interview and prior to a commercial break, Kimmel announced he would be asking about UFOs upon return. While Clinton concluded he found no evidence they exist, he said, "if we were visited someday, I wouldn't be surprised."

That wasn't enough for Ben Hansen, host of the TV show "Fact or Faked: Paranormal Files." His program features interviews with people claiming they've had paranormal encounters in order to confirm or debunk their stories. Following Clinton's appearance on Kimmel, Hansen said he was barraged by fans with questions.

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Hansen, who has a background in law enforcement and degrees in criminology and sociology, analyzed video of the interview, noting non-verbal cues of stress and evasiveness from Clinton's posture, eye contact and use of his hands. While Hansen acknowledged he is not an expert in non-verbal communications, he uses the skills regularly in his work.

Clinton – who had been using both hands as he talked, sitting with both feet on the floor – immediately adopted what Hansen described as a defensive stance, indicative of intention to conceal, when first asked about UFOs. Clinton began gripping firmly both arms of his chair and crossed his legs. For most of the remainder of their conversation about UFOs, Clinton's right hand stayed firmly anchored to the arm of the chair.

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Asked if he had investigated UFOs as president, Clinton said he had "sort of" during his second term, but then appeared to backtrack on the chronology, changing the topic to Area 51, the federal government's super-secret site in the Nevada desert. Clinton claimed Americans thought aliens were kept at Area 51 because workers there were required to wear special uniforms. But Hansen noted a leading Area 51 expert he consulted said Clinton's claim was novel and had never been made before.

Hansen identified incongruence between what Clinton was saying and his body language when asked about the Roswell incident, where a "flying saucer" allegedly crashed on a New Mexico ranch in July 1947. While telling Kimmel he had "everything" checked, Clinton was shaking his head no. Further, Hansen pointed to a 1995 General Accounting Office report that stated all administrative and communication files between 1946 and 1949 from Roswell Army Air Field had been destroyed.

At times, Clinton clinched his jaw, looked away from Kimmel and closed his eyes, all signs, said Hansen, that Clinton was experiencing stress or attempting to conceal his feelings. Other times, when UFOs were discussed, Clinton would stammer and change topic mid-sentence, something that disappeared when the topic changed.

Since Kimmel had announced Clinton's appearance on the show and his intention to ask about UFOs two days prior, Hansen reasoned Clinton should have been prepared and not caught offguard by the subject.

Clinton concluded by noting the vast size of the universe and recent discoveries of planets outside the solar system that might be suitable for life, saying it is "increasingly less likely that we are alone."

Kimmel jokingly jumped on the line, and again, noted Hansen, Clinton's answer showed stress and confusion.

"Oh, you are trying to give me a hint that there are aliens," Kimmel said.

"No," replied Clinton, all the while nodding his head yes.

Hansen said while analysis of Clinton's body language showed definite signs of evasiveness and intention to conceal and even deceive, it is impossible to say what the reason for it is.