6.1: INTRODUCTION

With no witnesses to the murders of Nicole Brown Simpson and Ron Goldman, DNA evidence in the O. J. Simpson murder case was the key physical proof used by the prosecution to link O. J. Simpson to the crime.

Over nine weeks of testimony, 108 exhibits of DNA evidence, including 61 drops of blood, were presented at trial. Testing was cross-referenced and validated at three separate labs using different tests with no discrepancies found. The prosecution offered the defense access to the evidence samples to conduct their own testing, but they declined.

The defense summarized their reasonable doubt theory as "compromised, contaminated, corrupted." They argued that, during the collection phase of evidence-gathering, the evidence was compromised by mishandling and 100% of the DNA of the real killer was lost; and then contaminated during the processing phase, with Simpson's preserved DNA being transferred to all but three exhibits. They alleged that the remaining three were corrupted as the police planted that blood evidence.

Due to its abundance and exhaustive validation, the prosecution considered the DNA evidence infallible. However, at this time the public was unfamiliar with the precision and significance of DNA matching, and the prosecution struggled to get the jury to appreciate this. The defense, on the other hand, had to change strategies after neither of their forensic DNA experts would support their theory. The new strategy, according to defense attorney Alan Dershowitz, intended to elicit a cherry-picking response from the jury whereby they would discard all of the "mountain" of DNA evidence against Simpson if they could show "a few of the hills" were corrupted by police fraud resulting in a jury nullification for the murders via an error of impunity. Although three exhibits were allegedly planted, by his closing arguments, lead defense attorney Johnnie Cochran had focused on a single exhibit: the bloody glove found by detective Mark Fuhrman at Simpson's Rockingham home.

After his acquittal, all of the DNA experts returned to testify in the wrongful death civil trial.

"Compromised, Contaminated, Corrupted"

The defense stated the DNA evidence against Simpson was not reliable. They said the police compromised the evidence by committing several mistakes when collecting it including occasionally not changing gloves between evidence items, using one swatch to collect blood from three drops of blood on the bronco dashboard, packaging the swatches of blood evidence using plastic bags, not paper bags as recommended, and storing them in a police van for up to seven hours unrefrigerated. This resulted in 100% of the "real killers" DNA being lost. They argued that Simpson's blood found on the evidence samples resulted from contamination in the LAPD crime lab with the reference blood in all but three exhibits. The remaining three exhibits that could not be explained by contamination were planted by the police. Although evidence of mistakes made during collection were shown at trial, no evidence of their contamination or corruption claim was presented.

The contamination claim was dependent on all the blood in the case being 100% degraded and the real killer's DNA lost. If that did not happen, contamination would only produce a mixture of Simpsons DNA and the killers. The contamination claim likewise would spread EDTA to the evidence samples which could be tested for as it was a preservative found in the reference vials of Simpson and the two victims. The contamination claim was also limited to just the LAPD crime lab as it was not alleged at the two consulting labs, the state department and Cellmarks diagnostics, were most of the DNA testing was done. The defense also declined to test the samples themselves for the “real killers” DNA or for EDTA.

Once the prosecution began showing evidence the samples were not completely degraded and no EDTA was found in levels seen from the reference vials, the defenses reasonable doubt theory became increasingly more dependent on the claim the evidence was corrupted by a police conspiracy to frame Simpson. The predominately African American jury was receptive to it.

Police conspiracy allegations

The defense conspiracy allegation of planted evidence primarily focused on three exhibits initially: the blood on the Bundy back gate, the blood on the sock from Simpson's bedroom and the glove found at his Rockingham estate. However, by the end of the trial the defense would eventually claim that virtually all of the blood evidence was planted by the police, including:

• the blood drops found next to the bloody footprints (match Simpson)
• the trail leading away from the victims (match Simpson)
• the blood on the back gate at Nicole Brown's home (match Simpson)
• the blood inside and outside Simpson's Bronco (matched Simpson and both victims)
• the glove found at Simpson's residence at Rockingham (match Simpson and both victims)
• the blood inside and outside of his home on Rockingham (match Simpson)
• the blood on the socks in his bedroom (match Simpson and Nicole Brown).

Bundy back gate

The defense claimed that one drop of blood on the back gate at Nicole Brown's Bundy Drive home was planted by the police. As evidence, they offered the blood contained EDTA, a preservative found in purple top tubes used for blood draws, it was collected several weeks later on July 3, rather than on June 13, and 1.5 mL of Simpsons donated reference blood was unaccounted for. The officer who planted it was not named by the defense. The prosecution countered that the EDTA levels found in the blood was consistent with that found normally in unpreserved blood and not even close to the levels found in blood preserved in a purple top tube. A different photograph of the gate on June 13 shows the blood was already there and the claim of some of Simpson's reference blood missing from the vial was refuted during rebuttal by the nurse who drew it who clarified he believes he only drew the amount the records show was used for testing.

The sock

The defense claimed that blood found on a sock in Simpson's bed was planted there by Detective Vannatter. As evidence, they offered that Vannatter did have possession of Nicole Brown's autopsy blood briefly prior to booking it into evidence and the blood contained EDTA, a preservative found in the reference vial of Nicole Brown autopsy blood. The claim was refuted by the defense's own witness, FBI special agent Roger Martz who showed the level of EDTA in that blood drop is consistent with unpreserved blood and not even close to the levels that would be seen in blood from a purple top tube. The prosecution also countered that no blood was ever claimed to be missing from Nicole Brown's reference vial and that the records show Detective Vannatter booked the reference vials from the victims immediately into evidence right after receiving it from Deputy Medical Examiner Dr. Irwin Golden. Dr. Cotton conclusively refuted that claim by showing the blood in the reference vial is substantially more degraded than the blood on the sock, proving it did not come from that vial.

Rockingham glove

The defense claimed that the bloody glove found at Simpson's Rockingham estate was planted by Detective Mark Fuhrman who said he found it there. No physical or eyewitness evidence ever surfaced supporting that claim. The only reason given at trial for believing that it was planted was of Fuhrman having perjured himself when claiming he had never used the word "nigger" in the last ten years.

The glove contained DNA from Simpson and both victims, and since the blood did not contain EDTA, the possibility of it coming from the reference vials was ruled out. Thus, if Fuhrman planted the glove at Rockingham from the crime scene, Simpson's blood would have to have been at the crime scene, contradicting his claim of being home on the night of the murders. Fuhrman's DNA was also not found on the glove, thus supporting his claim that he did not plant it. The prosecution argued that Fuhrman did not plant the glove because he did not know if Simpson had an airtight alibi that night. LA County Deputy District Attorney Vincent Bugliosi concurred with the prosecutor's argument, noting as well that Fuhrman did not know whose blood was on it at the time either.

Acquittal and aftermath 

All of the jurors were initially confident in their reasonable doubt about the DNA evidence. All maintain they understood the DNA evidence presented at trial and defended their decision in books and interviews. However, their confidence began eroding following events subsequent to the trial and acquittal of O. J. Simpson.

Civil Trial

A separate jury found Simpson to be liable for the murders in a civil trial one year after being acquitted in the criminal trial. Though civil liability has a lower burden of proof than guilty beyond a reasonable doubt, it is very rare for someone to be found liable for a crime after being acquitted for committing the crime (Turkcewiki.org).