Although this is an unusual situation that probably does not happen very often, I do not believe this is a conflict of interest. Probation officers are considered agents of the State and their role is really of that of a witnesses, eyes for the Court (much like police officers). I see no conflict between a probation officer being a witness in a case that is now disposed (since probation is a sentence, the final step of a case before it is closed).
Of course, if you believe that the probation officer is treating the probationer unfairly, unjustly, or is biased, document the instances that are examples of such behavior and contact the head of the probation department to get a reassignment and/or file a complaint.
Ernest A. Ryberg, Esq.
KOUFOS & NORGAARD, LLC
103 Brighton Avenue, Third Floor
Long Branch, New Jersey 07740
732.497.3467 (Mobile – Emergencies Only Please)