Also on Thursday's docket is a closed hearing on the 100-item questionnaire to be presented to the jury pool Friday.
A cornerstone of Kobe Bryant's defense is DNA evidence suggesting his accuser had sex with someone else soon after she said the NBA star raped her.
Just a day before Bryant is to go on trial, prosecutors are getting their chance to discredit that evidence.
They claim evidence at the defense-hired forensics lab was contaminated, reports CBS News Correspondent Lee Frank. A defense DNA expert is prepared to testify the alleged rape victim apparently had sex after leaving Bryant's resort room before going for a rape exam. While Bryant's lawyers challenge his accuser's credibility, prosecutors are challenging that of a key witness for the defense.
District Judge Terry Ruckriegle agreed to hold a hearing Thursday to decide whether the defense must prove the lab results are reliable.
Prosecutor Dana Easter said contamination was found in DNA control samples intended to ensure accurate testing. No details were included in the court filing, but prosecutors said they had concerns about Elizabeth Johnson, a defense expert who testified during a June hearing that the evidence suggests the alleged victim had sex with another man after her encounter with Bryant and before her hospital examination the following day.
That claim, which attorneys for the woman have denied, is a core part of the defense's strategy to undermine the accuser's credibility.
Contamination in control samples is less of a concern than contamination in samples taken from a defendant or alleged victim, said Scott Robinson, a defense attorney familiar with the case. But he said it could help prosecutors counter the defense expert's theories.
"If prosecutors can demonstrate there's reason to doubt the integrity of the defense lab, that will certainly help (their case)," he said. "With DNA technology, that's really about all you can do. Juries are so confused by the science involved, you've got to attack the evidence."
Phil Danielson, director of the University of Denver's Forensic Genetic Institute, said contamination in a control sample could give prosecutors ammunition to argue that DNA samples that do not match Bryant could have come from a lab technician, an investigator who gathered evidence, or even a worker at the plant where the testing materials were packaged.
Bryant, 26, has pleaded not guilty to felony sexual assault, saying he had consensual sex with the woman at the Vail-area resort where she worked last summer. If convicted, the Los Angeles Lakers star faces four years to life in prison or 20 years to life on probation, and a fine up to $750,000.
Bryant is not required to be in court for the hearing or Friday when 999 prospective jurors have been summoned to fill out questionnaires, but he is due in Eagle on Monday. Then he'll sit in a room with his attorneys, two prosecutors, the judge and, one-by-one, with each man and women being considered for the jury in Bryant's rape trial.