Criminal trial judges may be more sensitive to rumblings of dissent on juries now that a conviction has been reversed due to a juror mysteriously skipping out on deliberations.

The judge's replacement of the juror without exploring whether her absence was due to disagreements on the panel "impedes our careful scrutiny of the propriety of the substitution under these circumstances," a New Jersey appeals court held on Wednesday in State v. Musa.

The ruling means a new trial for Humfrey Musa, convicted of robbing a man of $31 on a Newark street.

After four hours of deliberations, jurors sent Essex County Superior Court Judge Robert Gardner a note saying they were "undecided" and asking whether a "particular juror could be excused from the case." The juror was not identified.

Gardner replied that "if a juror wishes to be excused, it has to be for a good reason, it can't be just because you're not getting along with the other jurors."

The law in New Jersey is that once a criminal trial is under way, a juror may be replaced due to illness or other inability to serve but not due to problems interacting with others on the panel.

When deliberations resumed the next day, Juror No. 2 failed to appear and gave no reason. She could not be located by court staff at home or at her job.

The defense lawyer, Assistant Deputy Public Defender Robert Blumenfeld, asked Gardner to investigate whether Juror No. 2 was the same one referenced in the note. Gardner declined to poll the jury.

An alternate was seated, and three hours after the reconstituted jury commenced deliberations, it found Musa guilty of second-degree robbery. He was sentenced to six years in jail.

Appellate Division Judges Paulette Sapp-Peterson and William Nugent ruled that due to Gardner's failure to conduct an inquiry, "there was no way to determine whether the juror's failure to return to court was for reasons personal to the juror or due to the juror's interaction with the jury."

Mutuality of deliberations entails the joint and collective exchange of ideas among individual jurors until a final determination is made, and that mutuality may be destroyed if a juror substitution is made not in accordance with court rules, the judges said. Hence, any conduct impacting juror deliberation must be carefully scrutinized.

When he received the note about excusing the juror, Gardner should have sought further clarification for the reasoning behind the question, they said. And when Juror No. 2 did not appear on the second day of deliberations, Gardner should have questioned remaining jurors to determine if there were any connection with the question in the note.

Musa's lawyer on the appeal, Assistant Deputy Public Defender Marcia Blum, says a trial judge is "supposed to look into it when there are problems that might have tainted the deliberations. He was asked to and declined."

Stephen Pogany, the Assistant Essex County Prosecutor who represented the state on the appeal, did not return a call. Chief Assistant Essex County Prosecutor Thomas Fennelly declined to comment.