An LAPD criminologist, Dennis Fung's responsibilities related to the analysis of crime scene evidence. As DNA evidence became significant in the Simpson trial, Fung spent more time on the stand than any other trial witness, testifying for a total of 9 days. As the prosecution's witness, Fung testified in detail as to how each of the blood drops and other pieces of evidence collected on the day after the murders. Fung admitted to having missed a few drops of blood on a fence near the bodies, but said that the returned several weeks afterwards to collect them..

On cross, Fung was asked repeatedly about the contamination of evidence. When asked about whether he kept the dog away, Fung stated, "when the dog got near the stains we'd shoo him away." Fung also admitted that he had not used rubber gloves when collecting all of the evidence.

Following his testimony, Fung was greeted with handshakes and hugs from the defense table where he was viewed as a hero. The defense later described him in their closing statements as a man who lied to cover up his involvement in the scheme to frame Simpson for murder.

Fung remained employed for the LAPD following the trial.