REDWOOD CITY, Calif. – A juror in the Scott Peterson murder trial who apparently did her own research on the case was removed and replaced with an alternate yesterday, and the judge ordered the panel to start all over again with their deliberations.

“We’re going to send you back. Start all over again and keep in touch,” Judge Alfred Delucchi told the panel on the fifth day of deliberations.

It was not immediately clear what the woman specifically did to get kicked off the jury. But a source said on condition of anonymity that she had apparently disobeyed the judge’s orders to consider only the evidence presented at the trial.

“You must decide all questions of fact in this case from the evidence received in this trial and not from any other resource,” the judge said.

The judge removed the juror after meeting behind closed doors with lawyers in the case. A day earlier, Mr. Delucchi lectured the jury about the importance of deliberating with an open mind.

The juror, a retired utility company employee in her 50s or 60s, was replaced with the next alternate – a woman in her 30s who worked at a bank and has four sons. Her brother was in and out of prison for drugs, leading her mother to become a drug counselor at a methadone clinic.

During the trial, the new juror seemed particularly attentive to defense presentations, and responded positively to the many jokes of defense attorney Mark Geragos. She smiled often and made a point of greeting the bailiffs each morning; she also cried at the sight of the autopsy photos.

Whether that means anything when it comes to deliberating the case remains to be seen, but lawyers for both sides left the courtroom smiling. Also unclear is whether the other members of the six-man, six-woman jury will be able to follow the judge’s orders and set aside any conclusions made so far in deliberating Mr. Peterson’s fate.

Mr. Peterson, 32, is charged with two counts of murder in the deaths of his wife, Laci, and the fetus she carried. Prosecutors claim Mr. Peterson killed Laci around Christmas Eve 2002, then dumped her weighted body from his boat into San Francisco Bay.

Dean Johnson, a former prosecutor who has been watching the case, said the ousted juror appeared to be sympathetic to the defense, judging from her statements during jury selection and her demeanor throughout the trial.

Her replacement, on the other hand, seems so emotionally involved in the case that it might be difficult for her to separate her feelings from the facts, Mr. Johnson said.

“She’s not going to be able to take her emotions out of the equation here,” he added.