In your case I believe the injured party appointed a
lawyer to prosecute a Criminal Case privately.
In other words, the injured party did not launch a criminal complaint to the police. Therefore, a Public Prosecutor was not involved in this case.
As a private Criminal Case, there will be a Preliminary Hearing in which a Judge will decide whether or not to accept the case for further trial. If the Judge accepts the case, there will be the official trial, at a later date.
Consequently, it is possible that you may have to testify as a witness of the Plaintiff on two occasions.
Rujira Bunnag