They focus on uncomfortable body language, which is not good, because men are often more uncomfortable telling the truth, than lying. It is one of the reasons they lie in the first place. It is more comfortable to say they did something, when they did not, for example. Men are uncomfortable talking to women in their emotional life because men fear what they see as our disproportional emotional response. They fear our tears and our anger. One response they have, is to lie. Another is to avoid. But that means that you can't tell from his being uncomfortable, or even with holding, that he is telling a real lie. Men often feel harsh things, and don't say them. It isn't always what needs to be said.
So if you look for uncomfortable, it could be the uncomfortable truth that you are missing out on.
So how do you catch a liar? The simplest rule is this: let him talk. Even be sympathetic in your voice. That's very important. Why? Because if he thinks you are suspicious, he will get careful. He will make sure he remembers things. If you quiz him with questions, he will try and close down discussion. If you press, he will get angry. Now that could mean he is protecting a lie, but it also could mean he wanted to tell you something and feels you cut him off. It also means he won't want to talk to you, because it is unpleasant.
No. Let him talk. Let him embellish. Let him go on. Now, after he has had a chance to talk, and you've drawn him out with sympathetic questions, look for two things.
The first is that he lacks details. In every important, or even moderately interesting moment, in our lives, we remember other details. While women are, in general, better at remembering details, that's not the case for really important moments. There is a freeze frame effect. We make associations. If a person is not telling the truth, but has created a story, they will have more trouble mentioning irrelevant details. Why is this? Because at the moment they were happening, we did not know them to be irrelevant.
The other crucial sign of a lie will come next. He looks too good. Men will, if they think they are getting a sympathetic hearing, as opposed to an interrogation, will try and turn things to proving their worth. They can't help it. Even if he looks bad, it is to look good, in the sense that he is playing for sympathy. Very rarely can men avoid taking the rope that you feed out.
So first, listen sympathetically. Once he gets going, ask about what seem to be irrelevant details. If a guy says he saw someone wearing a baseball cap, ask him which team. He will have noticed, because that is a thing he notices, just like he notices the size of a woman's breasts. Each time he must fabricate, it burns through more of his energy.
The problem with trying to unravel a thread, is that first it promotes hostility, and second, very few people's real stories hold together. In fact, if there are no loose ends, that is more often a sign that someone has gone over a story. Our real lives have holes in them, and we seldom are right about everything that did happen or why. Asking for explanations invites fabrication even when the person is telling the truth. Asking for details invites fabrication, only when it is already going on.
But this is in the context of his story, first let him get to his point, because his point, if he is lying, is the center. All roads lead to it. Until you know what he wants you to believe, you can't know what he is protecting.
So don't hang him by his thumbs, give him encouraging signs, and let him finally have story that collapses under its own weight, or is starkly absent of every thing that would mark it as real.