accessorial
adj. C1 Advanced ac·ces·so·ri·al
adj. describing something that is not the main part of a crime but helps someone else commit it. It is a legal word for being a helper or supporter.
adj. relating to the role of a person who assists or encourages another in the commission of a crime. Often used in legal contexts to distinguish between the principal offender and those who provide support.
The court decided the defendant was accessorial to the robbery.
In many jurisdictions, being accessorial to a crime can result in a lesser sentence than being the primary perpetrator.
The prosecution argued that while the defendant did not physically commit the theft, his accessorial role in providing the necessary tools and planning was sufficient for a conviction.
From accessory + -al.