Can a prosecutor share evidence that he is collecting for a trial against me with his friends who have nothing to relate with the trial?

The ethical rules discourage prosecutors from discussing pending cases with the media or the public in general. However, if a prosecutor does talk about a case, the remedy is not for a case to be tossed completely. Instead, other remedies are imposed depending on what was shared and how it was shared. Either side can ask for a gag order by the judge to prohibit open discussions. If a defendant feels that a community has been tainted by the prosecutor's comments, they can request a change of venue for their trial. If a gag order was already in place, the defendant can ask for sanctions against the prosecutor for violating the order. If the disclosures are particularly bad, a defendant could file a complaint with the state bar. The remedies are via motions and enforcement. But, generally, no, the entire case won't necessarily be invalid.

However, the "sharing" could still cause issues for the prosecutor that you could capitalize on for your defense. You don't define what you mean by sharing--- but if you are referring to only verbal communications-- you could make an argument for additional pieces of discovery in that the prosecutor has already waived any privileges by sharing the information with unrelated third parties. If by "share" you mean that he actually allowed a third party to pick up and handle physical evidence, you could raise issues regarding the chain of custody of evidence, thereby challenging its admissibility. Even though this seems like a distressing turn of events, the prosecutor's loose lips could actually harm them more than you in the long run if you leverage his/her disclosures to your advantage.

The ethical rules discourage prosecutors from discussing pending cases with the media or the public in general.  However, if a prosecutor does talk about a case, the remedy is not for a case to be tossed completely.  Instead, other remedies are imposed depending on what was shared and how it was shared.  Either side can ask for a gag order by the judge to prohibit open discussions.  If a defendant feels that a community has been tainted by the prosecutor's comments, they can request a change of venue for their trial.  If a gag order was already in place, the defendant can ask for sanctions against the prosecutor for violating the order.   If the disclosures are particularly bad, a defendant could file a complaint with the state bar.  The remedies are via motions and enforcement.  But, generally, no, the entire case won't necessarily be invalid.

However, the "sharing" could still cause issues for the prosecutor that you could capitalize on for your defense.  You don't define what you mean by sharing--- but if you are referring to only verbal communications-- you could make an argument for additional pieces of discovery in that the prosecutor has already waived any priviledges by sharing the information with unrelated third parties.   If by "share" you mean that he actually allowed a third party to pick up an handle physical evidence, you could raise issues regarding the chain of custody of evidence, thereby challenging its admissibilty.  Even though this seems like a distressing turn of events, the prosecutor's loose lips could actually harm them more than you in the long run if you leverage his/her disclosures to your advantage.