They do not look you in the eyes.
Being vague; offering few details
Repeating questions before answering them
Speaking in sentence fragments
Failing to provide specific details when a story is challenged
Grooming behaviors such as playing with hair or pressing fingers to lips
well I guess I don't need to answer after this lol oh and there's also that famous one shoulder shrug that means they're not being completely honest with you...
It depends on the person and what their "baseline" behavior is. Guidelines such as avoiding eye contact, or smiling nervously, or whatever are worthless unless you know what's normal for the person in question.
Yeah, I'm always fidgety, so my behavior always comes off as dodgy. It's only when I try to control myself that my family knows I'm um stretching the truth.
Hey; I've noticed that when YOU LIE, Erick; you keep your hands in front of you. You always look them straight in the eyes and hold your ground. Either that; or glare.
And you also refuse to let them speak.
-They avoid eye contact
-They seem nervous and keep moving
-They put a barrier between you, e.g. arms folded
-They look into your eyes and stand still unnaturally, like they're trying not to look like they're lying
-They stammer
-Their story doesn't sound real
-They hesitate
-They look nervous when you ask questions