The technique below can be adjusted to various situations – husband / wife, parents / children, boss / employees. The core idea is to introduce a made up fact and watch the reaction. It will tell you all you need to know. Remember: it’s all in details. 
More about liars and lying:
- All you need to know about pathological liars
- Signs of Lying in Body Language
- Body Language of a Liar
- Infidelity Warning Signs