Day 103 was dominated by disputes over DNA statistics, with defense attorney Peter Neufeld challenging the reliability and assumptions underlying Dr. Bruce Weir's population frequency calculations through cross-examination and recross. On redirect, Weir acknowledged errors and presented corrected calculations whose effects varied, while Neufeld elicited testimony about database limitations, percentages of the population not excluded, and omitted statistical adjustments. The day concluded with LAPD criminalist Denise Lewis beginning chain-of-custody testimony for evidence received from the Coroner's office and encountering an unexpected sealed bindle that required her to break a seal and renumber items.

• Neufeld exposes Weir's DNA frequency databases as convenience samples lacking proper racial classification and excluding Asian Americans.
• Defense demonstrates three-contributor mixture frequency could range from 1-in-2 to 1-in-3,500 depending solely on assumed racial composition of contributors.
• On redirect, Weir acknowledges errors in his mixture frequency calculations and presents corrected numbers whose effects vary across samples.
• Weir insists his multi-locus calculations are correct and says Neufeld's single-locus presentation tells only half the story.
• Neufeld's recross establishes that Weir's newly presented mixture frequencies omitted the FST adjustment and 99% upper confidence limit, both of which Weir agrees could make the discussed frequencies more common.
• Defense extracts admission that Weir's methods have never been used in any U.S. criminal court and he has never examined a DQ-Alpha strip.
• Defense objects to late discovery of 33 pages of materials including Susan Brockbank's notes, delaying her cross-examination.
• LAPD criminalist Denise Lewis discovers unexpected sealed bindle of soil and debris, forcing her to break seals on already-packaged Coroner's office evidence to maintain chronological integrity.