Definitely guilty of a crime or other misdeed; caught in the act. Thanks to footage from the security cameras, the police were able to catch the burglars dead to rights. The teacher came up behind us as I was copying Lewis's test and caught us both dead to rights. The officer had the gangster dead to rights, having discovered several kilograms of narcotics hidden in the back of the vehicle.

in the act; (guilty) without question. We caught her dead to rights with the loot still on her. There he was, bang dead to rights with the smoking gun still in his hands.

In the act of committing an error or crime, red-handed. For example, They caught the burglars dead to rights with the Oriental rugs. This phrase uses to rights in the sense of "at once." [Slang; mid-1800s]

In the very act of making an error or committing a crime: The police caught the thief dead to rights with my silverware.

Absolutely without doubt; also, red-handed, in the act of doing something. The term originated in the United States in the mid-nineteenth century and was used mostly with reference to criminal activity. George Washington Marsell defined it in his Vocabulum or The Rogue’s Lexicon (1859): “Dead to rights [means] positively guilty and no way of getting clear.” It is heard less often today.