How to detect liars

I came accross a great site to detect liars. I have selected few points. Visit the site on how to detect liars for more information.
The following techniques to telling if someone is lying are often used by police, and security experts. This knowledge is also useful for managers, employers, and for anyone to use in everyday situations where telling the truth from a lie can help prevent you from being a victim of fraud/scams and other deceptions.
• Physical expression will be limited and stiff, with few arm and hand movements. Hand, arm and leg movement are toward their own body the liar takes up less space.
• Timing and duration of emotional gestures and emotions are off a normal pace. The display of emotion is delayed, stays longer it would naturally, then stops suddenly.
• A guilty person gets defensive. An innocent person will often go on the offensive.
• A liar will use your words to make answer a question. When asked, “Did you eat the last cookie?” The liar answers, “No, I did not eat the last cookie.”
• If you believe someone is lying, then change subject of a conversation quickly, a liar follows along willingly and becomes more relaxed. The guilty wants the subject changed; an innocent person may be confused by the sudden change in topics and will want to back to the previous subject.