How ac you figure out someones lying
1. he/she starts touching his/hers ears and facial area more. 2. tries to change subject. 3. looks away. 4. starts blinking more frequently. 5. tells more details than needed. 6. can't follow his/hers story.
if their expression changes
well if they told you one thing and posted something different at that time on facebook,asking them,strange behavior that you didn't see before