Dr. Bruce Weir was a prosecution witness and population geneticist who presented frequency calculations for mixed blood stains, including calculations involving the Bronco. Over three days in June 1995, defense attorney Peter Neufeld extensively cross-examined him about his mixture methodology, its relationship to National Research Council guidance, and omitted genotype pairs in the Bronco calculations; Weir later acknowledged errors and presented corrected calculations whose effects varied. In August 1995, defense expert Dr. Terence Speed disputed a prosecutor's assertion that Weir's population-frequency estimate was the only statistical information before the jury.