Day 79 featured intensive cross-examination and redirect of DOJ DNA analyst Gary Sims on the core DNA evidence from the Bronco and Bundy locations. Barry Scheck challenged the DNA evidence by comparing higher DNA yields in September samples with June samples under a disputed same-general-area assumption and suggesting contamination or tampering. He also questioned the enormous DNA quantities in the socks and argued that DQ-Alpha control activity required repeat analysis. Sims described faint cross-hybridization rather than an incorrect allelic-control result and disputed Scheck's interpretation. Rockne Harmon conducted extended redirect examination, walking Sims through DQ-Alpha and D1S80 results, questioning whether charts and hypotheticals omitted additional test data, and eliciting testimony about the lab's controls and methodology. The testimony addressed the reliability and interpretation of the prosecution's DNA evidence.

• Scheck establishes that Bronco samples collected Sept 1 contained dramatically more DNA than the same areas collected June 14 (40.5 ng vs 2.6 ng), which he used to suggest contamination or tampering
• Scheck attacks DQ-Alpha typing of stain 31 for having a questionable 1.3 allele dot that per protocol should have triggered reanalysis
• Using a 37-combination genotype chart, Scheck demonstrates only 2 of 37 possible combinations in Bronco stain 303 include both victims' DNA together
• Scheck shows that 27-36% of the general population cannot be excluded as source of key allele on steering wheel stain
• Harmon redirects Sims through DQ-Alpha and D1S80 results, asking whether defense charts and hypotheticals omitted additional test data and questioning him about controls
• Rehybridization of Bundy item 52 confirmed Sims' original 1.1, 1.2 call, according to prosecution testimony
• Sidebar dispute arises over whether redirect can include rear gate stain evidence using EAP/PGM markers; Ito allows limited redirect but signals no broader retrial