how did you know she was lying? give me tips for catching him out
look directly into his eyes, if he's not looking directly at you then there is a chance he is lying, if he is looking anywhere else but at you, he is lying.
Also watch his body language, if he looks like he's hiding something, arms crossed or making his body small then he is closing up, which means there is a good chance he is lying.
If his body is relaxed and open then it means he is not hiding anything, then there is a good chance he is telling the truth.
How long does it take him to answer, there is a good chance if he is lying it will take him a while to come up with an answer, on the other hand if he just comes out with an answer then there is a better chance he is telling the truth. This third point though is the most unreliable out of the three, they eyes and body language are most important to watch