Definition - What does Accomplice Witness mean?
An accomplice witness is someone who takes part in a crime. A person does not need to take part in the crime while it is being committed to be an accomplice witness. Instead, a person can be an accomplice witness by helping a crime take place before, during or after the actual crime is committed.
Justipedia explains Accomplice Witness
People who know about crimes and who do not report them are not accomplice witnesses. Only those who help the crime take place are. In the following situation, all would be accomplice witnesses: one man cuts the surveillance camera outside of a bank one day in advance, three men rob the bank the next day, and one man goes back into the bank the next day to destroy evidence. This is because they all helped the crime take place, and so they could all be charged with the crime.