India, Nov. 12 -- A former undercover CIA officer has revealed how to spot a liar, explaining why changes in body language, unusual reactions and inconsistencies in a conversation can offer clues that someone is hiding something.

Michele Rigby Assad, who spent 10 years working undercover for the CIA in the Middle East, learnt to recognise such behavioural changes while assessing intelligence sources. Her experience offers an insight into the subtle signs that can give away someone concealing information.

In an interview with Business Insider, Assad recalled assessing an Arab intelligence officer suspected of secretly working for another country's intelligence service.

She spent hours speaking to him, first observing his usual body lang...