A cooperator., An associate in the commission of a crime; a participator in an offense, whether a principal or an accessory.
A mate; a partner; esp., an accomplice or confederate.
Accomplice. Or it could be an Abettor.
accomplice
I was the accomplice to a crime
The plural of accomplice is accomplices
Accomplice is a noun.
An accomplice is somebody who joins in with an activity of another person. Usually an accomplice is somebody that has helped a person commit a crime.
He is the accomplice of this crime.
The bank robber had an accomplice waiting outside in a car.
The man was arrested for robbery as an accomplice to the main suspect.
The Accomplice - 1915 is rated/received certificates of: USA:Approved
The question asnwered itself. you will be charged as an Accomplice to Murder.