Gregory Matheson, the LAPD's chief chemist and a prosecution scientific witness, testified over five consecutive trial dates in May 1995, with direct examination by prosecutor Hank Goldberg and cross-examination by defense attorney Robert Blasier. He addressed serology results, evidence-collection and chain-of-custody procedures, and testified that crime-scene blood drop 49 could have been donated only by O.J. Simpson, excluding Nicole Brown Simpson and Ronald Goldman. Blasier elicited testimony about the laboratory's lack of accreditation and absence of a formal field-operations manual and advanced a conditional calculation involving approximately 1.5 milliliters of Simpson's reference sample as part of the defense's evidence-planting allegation; redirect and recross revisited the blood-vial accounting and the assumptions underlying that figure.