An accessorysupposes a principal offender. One who is neither the chief actor in an offense, nor present at its performance, but accedes to or becomes involved in its guilt, either by some previous or subsequent act, as of instigating, encouraging, aiding, or concealing, etc., is an accessory.
An accomplice is one who participates in the commission of an offense, whether as principal or accessory. Thus in treason, there are no abettors or accessories, but all are held to be principals or accomplices.
(supporter): Nowadays it usually refers to a reprehensible act that is supported.