The duty to preserve evidence begins once any state agency or actor has gathered and taken possession of evidence as part of a criminal investigation. Law enforcement doesn’t need to preserve all evidence it collects. The duty to preserve extends only to evidence that might be expected to play a significant role in the suspect’s defense: “material” and “exculpatory” evidence Per the Brady v. Maryland decision, prosecutors have a duty to disclose exculpatory evidence even if not requested to do so. Prosecution is not required to search for exculpatory evidence and must disclose only the evidence in its possession, custody, or control. The prosecution's duty is to disclose all information known to any member of its team (LE, investigators, crime lab, etc) IMO, Kibby's defense is crying about the lack of given in the affidavit of probable cause. This may just be a simple tactic to try to obtain as much info/evidence that LE has, in order to "level the playing field". I play for the good guys, not the bad guys. Maybe an attorney on board can explain this better.