FBI hair and fiber expert Douglas Deedrick spent the entire day on the witness stand, first providing prosecution testimony linking trace evidence to Simpson's Bronco, the victims, and alleged clothing, then enduring a systematic defense cross-examination that challenged the scientific validity of hair microscopy and exposed investigative gaps. The proceedings showcased a fundamental clash between the prosecution's fiber narrative and the defense's attack on the methodology underlying that evidence.

• Deedrick testified that distinctive tri-lobal nylon carpet fibers from Simpson's Bronco were found on the Rockingham glove and blue knit cap
• Blue-black cotton fibers consistent with a dark sweatsuit were linked to the Rockingham glove, Goldman's shirt, and Simpson's socks
• Bailey established that hair microscopy lacks standardized methodology and relies on subjective 'eyeball' comparison rather than formal protocols
• Bailey highlighted investigative failures including missing samples from crime scene personnel and a second knit cap discovered at Bundy that was never properly processed