I have been doing a few tests in my everyday life and one person i have been observing is my dad. He tends to lie for a joke quite a lot and i can usually tell when he is lying.
One thing he does, is just not blink at all until i have said something back. He will also not look me directly in my eyes and he usually looks lower at my mouth or chin to avoid this. so with the unbroken eye contact and not looking me dead in the eyes indicates to me that he is lying. However i do look at his body language to back up my answer. He usually freezes completely until i have spoken back, and he has no facial expressions what so ever until i speak back too.
With all these small hints to back up my answer i just say to him that he is lying and then he is start laughing. I usually get this 100% of the time with him as he is so easy to spot when he is lying, but other people may be much harder to read. Look at my post about how to spot people when they are lying.