Arraign is when someone is called to court for a criminal charge. It can also mean that someone was found with fault.
It's called an accomplice, or a co-conspirator.
a murderer?
That person is an accessory or an accomplice.
a customer helper
Someone who sells houses is called a realtor.
. . . is a criminal, or an offender, or an arrestee, or a defendant. or a misdemeanant, or a felon . . . . etc.
breaking the law would constitute a criminal case.
Depending on the circumstances... either vandalism or criminal damage.
A proponent is someone who supports criminal justice or a criminal justice system.
"one who assists a criminal" a 7 letter word
A criminal is someone that has been convicted of a crime. Once that has happened they are considered a criminal.