Prof. Herbert MacDonell, a forensic scientist and bloodstain pattern analyst from Corning, New York, testified as a defense witness in late July and August 1995, called by Peter Neufeld to directly challenge the prosecution's interpretation of blood evidence found on socks recovered from O.J. Simpson's bedroom. MacDonell's central claim — that ankle stains on the socks were consistent with planting rather than being worn during the murders — made him a linchpin of the defense's evidence-tampering narrative. Prosecutor Marcia Clark subjected him to extensive cross-examination that attacked his methodology and credibility, and when he returned during the civil trial, plaintiffs' counsel exposed significant inconsistencies in his observations, noting his counts of blood spheres on the socks shifted from testimony to testimony — all made without contemporaneous notes from an uncertified home laboratory.