To unmask a liar, simply ask them these two questions: the psychological technique that reveals contradictions

For example:
“Who exactly was present?”
“What was happening around them at that moment?”
“And just before that, what happened?”

A sincere person usually remembers secondary details, even the most trivial ones.

On the contrary, someone who improvises will tend to be vague or limit their answers, for fear of contradicting themselves.

Signs to observe (without jumping to conclusions)
These questions primarily allow us to observe:

Changes in the narrative
Unusual breaks
Details that vary
Difficulty responding spontaneously
However, none of these elements alone proves that a person is lying.

Stress, fatigue, or an imperfect memory can also explain some doubts.

A useful method… but one that should be used with caution.