hired vindicator
A "copycat" crook who is employed by a suspect in a recent crime to discreetly (i.e., without being recognized or caught) commit one or more similar crimes in the area while the suspect is in custody, thereby "proving" that the suspect isn't the one guilty of the "original" crime, since more crimes of the same type are being committed while he himself is out of circulation and thus could not possibly have committed them.
Being a hired vindicator might have its advantages, but it can also backfire, in that crimes committed by others can be falsely pinned on you. For example, Person A commits a burglary, and then sometime later is arrested and detained as a possible suspect, despite his professing his innocence. Person A's cronies then hastily scatter around and hire Person B to commit a string of additional burglaries in Person A's local area in an effort to draw suspicion off of Person A. But then one or more other local crooks commit subsequent burglaries in the same general vicinity, and so if Person B is eventually apprehended, he will likely be suspected of **all** of the burglaries, including the ones committed by these "new" criminals.