Extraneous offense refers to an offense that is beyond or unrelated to the offense for which a defendant is on trial.
An extraneous offense may be admitted into evidence without violating the Due Process Clause if there is a strong showing that the defendant committed the offense and if the extraneous offense is rationally connected with the offense charged. [Story v. Collins, 920 F.2d 1247 (5th Cir. Tex. 1991)]