Speak with the prosecutor and they will review and determine if this can be used as evidence or not as provided under your state rules.
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As with most things in the law...the answer is "it depends." The Idaho Rules of Evidence govern the admissibility of such things. As the previous poster indicated, the prosecutor will be able to speak more fully to whether the screen-shot is admissible under the facts and circumstances of the case.
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Authentication may be the issue. As a witness, you will want to cooperate readily with the prosecutor on this an every other issue of proof.
Best wishes for a favorable outcome, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.