You will need
To determine a lie, carefully follow the body language of others. For example, a sure indication that the person is lying - that he's avoiding to look you in the eye or behaves nervously.
Notice the incoherence and inconsistencies that tells you people. Remember all the time frame described incidents, errors and mixing of parts, different interpretations of the same story. All these things will help you to identify a lie.
A clear sign, by which to determine a lie, is the reluctance of peopleto answer any questions. If he behaves aggressively in response to inquiries, the more likely he is hiding something.
If your partner is trying to accuse you of lying when there's no obvious reason this may indicate that he is cheating on you and. Accusing you, he projects his emotions to the outside, thereby reducing the guilt.
In some cases, to determine the lie helps the intuition that tells you that person is lying. But don't try to go straight to the charges, explain your feelings and guesses with evidence.
Ask the interviewee directly, he is lying or not. Many people feel terrible when they are caught red-handed, and wish to ease the soul confession.