An unusual verbal exchange took place Thursday in the hallway between Juror No. 5 and Laci Peterson's brother in the double-murder trial of husband Scott Peterson (search).

The exchange was caught on tape by media who make up the press pool in the courthouse. The audio on the tape is garbled but the juror can be heard saying to Brent Rocha (search), "you are going to lose today."

It was unclear exactly what the juror was talking about.

This juror has also been seen by courtroom observers exchanging pleasantries with Scott Peterson's lawyer, Mark Geragos (search).

Stan Goldman, a Fox News legal analyst, said Brent Rocha's reaction was just a pleasant smile in return. Goldman noted that there are six alternate jurors if the judge decides the behavior is too inappropriate.

"He [judge] may very well kick him off — they've got these alternates — they can replace him," Goldman said, but warned that if all the alternates are used up as replacements or if a juror is out sick, that could, in the end, result in a mistrial or dismissal of the case.