The posting was on a MySpace page described as "Team Spector," said Steve Whitmore, a spokesman for the Los Angeles County Sheriff's Department.
Whitmore would not comment on the wording of the posting, but Superior Court spokesman Alan Parachini said it contained the words "I love Phil Spector" and "The Evil Judge should DIE!!!!" and was signed "xoxo Chelle." The posting has been removed, he said.
Spector's wife is named Rachelle, but one of the producer's defense attorneys, Christopher Plourd, said she denied having anything to do with the posting.
Rachelle Spector, a 27-year-old self-described musician, recently clashed with Superior Court Judge Larry Paul Fidler when he scolded her about giving a TV interview and then e-mailing reporters about it. The judge imposed a gag order on her and others after she talked back to him in court.
Tuesday marked the 11th day of jury deliberations, but some of those days have been very short. The jury recessed deliberations Tuesday afternoon and was to resume talks Wednesday.
Spector, 67, is charged with second-degree murder in the Feb. 3, 2003, death of Clarkson, 40. She was killed by a gunshot fired in her mouth as she sat in the foyer of Spector's mansion after meeting him at her job as a nightclub hostess.
Spector emerged on the music scene in the late 1950s and became a top producer using a hit-making recording technique that became known as the "Wall of Sound." His prominence faded after the 1970s.
Clarkson was best known as the star of Roger Corman's 1985 cult film "Barbarian Queen" and another way-out film, "Amazon Women on the Moon," and had a string of bit parts on sitcoms including "Three's Company."
The defense contended Clarkson was depressed and the shot was self-inflicted, either an accident or a suicide.
The case went to the jury Sept. 10, and the foreman told the judge on Sept. 18 that the panel was deadlocked. After two days of debate among attorneys, the judge revised jury instructions, and the panel resumed talks late Thursday.
By Linda Deutsch