The FayObserver reports that:

The judge in the court-martial of Army Master Sgt. Timothy Hennis rejected defense calls for a mistrial this morning. Defense lawyers claimed that the judge, Col. Patrick Parrish, acted with partiality – or the appearance of partiality – in front of the jury Monday, leaving the impression that the defense was trying to hide evidence.

EvidenceProf Blog has this:

Judge, Jury, And interrogator, Take 3: Seventh Circuit Doesn’t Reverse Despite Improper Judicial Interrogation

Federal Rule of Evidence 605 provides that:

The judge presiding at the trial may not testify in that trial as a witness. No objection need be made in order to preserve the point.

Conversely, Federal Rule of Evidence 614(b) provides that “[t]he court may interrogate witnesses, whether called by itself or by a party,” and Federal Rule of Evidence 614(c) provides that

Objections to the calling of witnesses by the court or to interrogation by it may be made at the time or at the next available opportunity when the jury is not present.