Phil Spector's fate could ultimately hinge on a hearing Thursday.

That's when a Los Angeles judge is set to decide whether a purported confession attributed to Spector should be admitted as evidence in his upcoming murder trial.

Last week, prosecutors filed a petition with Superior Court Judge Larry P. Fidler requesting a jury be allowed to hear incriminating statements made by the famed record producer in which he told police he "didn't mean to shoot" B-movie star Lana Clarkson.

Deputy District Attorney Douglas Sortino also asked the judge to bar Spector's defense team from bringing up in court their claim that the actress killed herself, or as Spector's told Esquire magazine, that she "kissed the gun."

Clarkson was found shot to death in the foyer of Spector's suburban Los Angeles mansion in the early morning hours of Feb. 3, 2003.

The 65-year-old music maven, best known for his innovative Wall of Sound orchestrations and collaborations with legendary acts like the Beatles, Righteous Brothers and Ronettes, has pleaded not guilty and is free on $1 million bail. His trial is expected to get underway sometime in January, though an exact date has not been set.

According to prosecutors, Spector copped to the crime soon after he was taken into custody.

"I'm sorry this happened. The gun went off accidentally," he is quoted as saying in a police report.

Spector's chauffeur, Adriano De Souza, who called 911 the day of the murder, told the dispatcher he saw Spector brandishing a gun, adding, "I think my boss killed somebody."

The legal maneuvering by prosecutors came in response to a motion filed by Team Spector two weeks ago, asking the judge to bar the statements because the eccentric music man was "experiencing symptoms of withdrawal" from medications at the time he was interrogated. Those symptoms may have included "hallucinations, forgetfulness, serious fatigue and/or slurring," Spector's lawyers argued in the motion. Spector had been prescribed a veritable pharmacy's worth of drugs, including two different antidepressants, two drugs to combat seizures, an antacid, migraine medicine and an antibiotic.

Spector's attorneys also want Fidler to prohibit evidence related to Spector's history of misdemeanor weapons convictions and to keep jurors from hearing about 14 guns confiscated from his estate.

Additionally, in court papers filed Monday, Cutler and company seek to block an effort by prosecutors to present as evidence a copy of a deposition the legendary producer gave in a separate civil suit against his former attorney, Robert Shapiro (best known as one of O.J. Simpson's so-called Dream Team).

Spector sued Shapiro and his law firm asking to refund part of a $1 million retainer after Spector replaced Shapiro with Bruce Cutler and Roger J. Rosen.

Sortino's office has subpoenaed the transcript and videotape of Spector's testimony taken on July 19.

But Cutler and Rosen maintain the documents in question are "protected from disclosure by attorney-client privilege." They said that Shapiro and Spector "agreed that the deposition transcript would remain confidential, for attorneys' eyes only" and that Spector would never have agreed to the deposition if he knew prosecutors in his murder case would try to use the testimony against him.

"I don't know what's it's in there, but as I understand it, the deposition was taken under a confidentiality agreement and...that confidentiality should be enforced, otherwise there's no reason why Mr. Spector's deposition would've gone forward," Rosen said Wednesday.

Fidler will begin hearing arguments on the supposed confession Thursday morning; the hearing is expected to last several days. The judge set a Dec. 2 date to take up the motion involving Spector's deposition.