The attorneys for the man convicted of killing former congressional intern Chandra Levy have asked a D.C. Superior Court judge for a new trial, arguing that prosecutors withheld key information about a witness, officials said.

The new information about the witness was passed to local prosecutors from prosecutors in California, where the witness had lived, according to an official with knowledge of the case. Prosecutors went to Judge Gerald I. Fisher with the new information, but defense lawyers are alleging that the government had already had it during trial, officials said.

Fisher must decide whether local prosecutors knew of the information before the trial and intentionally withheld it from defense attorneys, and whether that information would have resulted in a different verdict.

Ingmar Guandique, 30, a Salvadoran who is in the United States illegally, was convicted in 2010 of first-degree murder charges after an eight-week, high-profile trial. He later was sentenced to 60 years in prison. The Levy case drew national attention because the intern was having an affair with a congressman from her home town in California.

It is unclear which trial witness is at the center of the request for a new trial or what information has emerged about the witness. That is because arguments in the proceedings about the the new information were restricted to lawyers and the judge, and the transcripts of those hearings are sealed. The hearings began last month and the most recent one was Jan. 4; the next is scheduled for Feb. 7.

This undated file photo released by the family shows Chandra Ann Levy. (Modesto Bee/AP)

William Miller, a spokesman for the U.S. attorney’s office in the District, declined to comment. Julia Leighton, general counsel for the District’s Public Defender Service, which represents Guandique, said in a statement: “We object to the protective order issued by Judge Fisher in this case, which prevents us from discussing the current proceedings, but so long as it is in place we have and will continue to have no comment.”

The officials who spoke about the request for a new trial did so on the condition of anonymity because of the judge’s sealing order.

It is not unusual for defense attorneys to file motions of appeal on behalf of their clients who are found guilty at trial. One argument commonly used is that prosecutors failed to disclose evidence. Prosecutors must hand their evidence to the defense at the earliest possible time, even if that evidence weakens their case. Failure or a delay in doing so can be considered misconduct and a violation of a 1963 rule based on the Supreme Court case Brady v. Maryland.

Defense lawyers have long complained that some prosecutors in the U.S. attorney’s office hamper their investigations by withholding evidence or keeping it until the last minute. Prosecutors say such complaints are tactics to try to delay or secure new trials. Judges generally have sided with prosecutors, and the granting of a new trial is rare.

Fisher oversaw Guandique’s original trial. If he rejects the defense request for a new trial, Guandique’s attorneys are likely to go to the D.C. Court of Appeals.

Levy, 24, disappeared on May 1, 2001. Her remains were found a year later in Rock Creek Park, where she had gone for a jog.

It was a challenging case for prosecutors. Guandique had repeatedly denied involvement in Levy’s death. There was no DNA or forensic evidence linking Guandique to the crime. There was no weapon, no eyewitness and no official cause of death. Prosecutors’ key evidence was the testimony of one of Guandique’s former cellmates, who told the jury that Guandique admitted to him that he had killed Levy. Prosecutors also proved Levy’s attack was part of a pattern by Guandique.

In 2002, Guandique pleaded guilty to assaulting two other women in Rock Creek Park about the time Levy disappeared.

Levy’s disappearance and death had emerged as one of Washington’s most sensational murder cases when it was discovered that she had had an affair with Gary A. Condit, the married congressman who was 30 years her senior. Condit was the first suspect in Levy’s disappearance and later was cleared.