I have discovered that when you are asking someone questions, because you are trying to gain clarification about something, and you start to figure out that they are lying, sometimes they get defensive and accusatory. Sometimes they will change the topic or come up with lame excuses.
And they will not admit that they are lying.
If you accuse them of lying they will just deny it, and turn it around and accuse the accuser. Kinda like Fauci did to Rand Paul.
I have found that it is better to back off and prove the lie later.
And I will make a mental note that the person is a liar for future reference.