body language but not behaviour. Liars have to pause to make the story up and add detail in their head before sharing. Interrogation will go forwards backwards, high level and zoomed in, in order to trip the liar up as they struggle to piece the story together. Someone telling the truth will largely just share. Skilful liars are able to convince themselves and imagine the whole fiction.
Some people look dishonest even when telling the truth, sadly a lot of the unlucky ones end up getting convicted.