Idaho Code § 19-2125: Disclosure of facts known by juror.

If a juror has any personal knowledge respecting a fact in controversy in a cause, he must declare the same in open court during the trial. If, during the retirement of the jury, a juror declares a fact which could be evidence in the cause, as of his own knowledge, the jury may return into court. In either of these cases, the juror making the statement must be sworn as a witness and examined in the presence of the parties.