I personally think Bernie Sanders is behaving in an appalling manner which would not be acceptable if the shoe was on the other foot and the DNC really had no choice but to question and investigate this matter. No matter how you slice it, the Sanders camp stole strategic information which really no one has any way to determine if they copied it through a camera or not. Nevertheless after the Sanders sued the DNC and after cooperation from the Sanders camp, the DNC has given access back. In my opinion, they should went to court with it and let a judge make them do it. I mean the DNC and the Hillary camp are already accused of favoring the Hillary camp so they may as well have continued on until they got to the bottom of it.
To put it in yet another analogy, if someone leaves a hundred dollar bill left on a kitchen table in a family, if someone else in the family takes it, then they are taking something that doesn't belong to them regardless of it having been left out.
Sanders regains access to voter files after bitter fight over data breach