How might a careful observer of nonverbal know when they are not being told the truth?

A careful observer of nonverbal cues may notice inconsistencies between a person's verbal statements and their body language, such as avoiding eye contact, fidgeting, or closed-off postures. Changes in vocal tone, pitch, or pace can also indicate discomfort or deception. Additionally, micro-expressions—brief, involuntary facial expressions—might reveal true emotions that contradict the spoken Words. These subtle signals can suggest that the person is not being entirely truthful.