Gregory Matheson, the LAPD's chief chemist, testified in the preliminary hearing, criminal trial, and civil trial about serology, evidence collection, and chain of custody. In the criminal trial, he testified that blood drop 49 could not have come from Nicole Brown Simpson or Ronald Goldman and could have come from O.J. Simpson; he estimated the matching profile at approximately 0.43 percent of the population, about one person in 200. His criminal-trial cross-examination also addressed laboratory accreditation, field procedures, and blood-vial accounting.