There is no single behavior indicative of deception. While you're looking for some clues, don't jump to conclusions.
Proponents of neuro-linguistic programming claim that certain eye-movements are reliable indicators of lying. For instance, if a person is looking up to their right, this eye behaviour suggests a lie, whereas looking up to their left is indicative of truth telling.
Despite widespread belief in this claim, results of previous studies fail to support it.
In Study 1, the eye movements of participants who were lying or telling the truth were coded, but did not match the NLP patterning.
In another experiment, one group of participants were told about the NLP eye-movement hypothesis whilst a second control group were not. Both groups then undertook a lie detection test. No significant differences emerged between the two groups.
Study 3 involved coding the eye movements of both liars and truth tellers taking part in high profile press conferences. But once again, no significant differences were discovered.