accomplice
n. countablen. a person who helps someone else commit a crime or do something wrong. You use this word for someone who is a partner in a bad act.
n. a person who knowingly, voluntarily, or intentionally gives assistance to another in (or in some cases as) the commission of a crime.
The police are still looking for the thief's accomplice.
The driver of the getaway car was charged as an accomplice to the bank robbery.
While he did not pull the trigger himself, the prosecution argued that his role in planning the heist made him a willing accomplice to the murder.
First attested in 1550. From a complice, from Middle English complice, from Old French complice (“confederate”), from Latin complicāre (“fold together”). The article a became part of the word, through the influence of the word accomplish.
Often used with the preposition 'to' when referring to a specific crime.
an accomplice of the robberyan accomplice to the robberyWhen linking an accomplice to a specific crime, the preposition 'to' is standard; 'of' is used for the person they helped.