Prosecutors said they had found contamination in DNA "control" samples intended to ensure testing was accurate. They also said data from the defense's experts appears to have been manipulated.
Prosecutors asked the judge to hold a hearing Thursday to force the NBA star's attorneys to prove the reliability of the evidence intended to be presented at trial by defense experts.
Those experts include Elizabeth Johnson, who testified in a closed-court hearing in June that DNA evidence strongly 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.
In the filing, prosecutor Dana Easter said some data from Technical Associates Inc., the California firm where Johnson works, appeared to have been "whited out or otherwise manipulated."
Easter also said the defense had refused to provide prosecutors with unspecified information and documents, and that contamination was present in samples that should have provided known results to ensure the accuracy of testing. Easter also said Technical Associates has conducted testing earlier this month but not provided prosecutors with results or data from those tests.
"Usually these sorts of disputes are resolved long before trial or they are resolved during trial with one side or another raising questions about reliability while an expert witness is on the witness stand," reports CBS News Correspondent Andrew Cohen.
And that's the likely result here, says Cohen.
"I think the judge will deny this prosecution request but allow the DA to raise this issue with the defense witness once she takes the stand."