yesAlso is there any chance of me receiving a conviction based on witness testimony alone?
they do have something to gain; prosecuting a thief so hopefully that person learns to not be a thief and others will know that this store is serious about prosecuting thieves.Is it likely that he will show even if he has nothing to gain since no item was stolen?
if the star witness doesn't show again, your lawyer should make a motion to dismiss if the prosecution is not willing to go to trial without the witness. Without knowing more about the situation, it is impossible to determine if the DA will go ahead to trial without the witness or if the judge will grant the dismissal since the DA keeps delaying this for the reason they are.
if they consider this a violation of your probation, yes but as it is from the same case, I wouldn't think they would but...I have taken a plea deal on a charge which happened at the same time as this one. ( Ordinance violation , given supervision apparently charged as a felony) If I am convicted on this charge is there any chance of jail time?
what is this charge and why was it tried separately? That is the oddity here.

