Gary Sims, Renee Montgomery, Steven Myers and Ken Konzak
California Department of Justice DNA Laboratory, Berkeley, CA
The Department of Justice DNA Laboratory's involvement in the case of People of the State of California v. Orenthal James Simpson began on July 26, 1994. At that time we were asked by the Los Angeles County District Attorney's Office about the possibility of running a few samples using the long-established RFLP (Restriction Fragment Length Polymorphism) technology. We were also asked about performing some analyses using the PCR (Polymerase Chain Reaction)-based D1S80 test. At the time, this was a relatively new test that we had brought on-line for casework in the Spring of 1994. By the end of our analysis, we had received 61 items of evidence and extracted 108 samples in 22 sets. We also co-extracted 21 quality control samples (bloodstains whose types are unknown to the analyst) along with 24 extraction reagent blanks.
With the exception of the initial reference specimens and a hair, all of the examined items were initially opened and documented in the presence of defense expert Dr. Edward Blake of Forensic Science Associates in Richmond, CA. Documentation included notes, sketches, photography, measurements, and weighing (of stain swatches). After the initial examination and documentation, portions (generally about half, with some exceptions) of the samples were removed for DNA extraction. After extraction, the DNA was evaluated for quantity and (sometimes) quality, in order to assess which DNA typing tests (RFLP versus PCR) were appropriate for a particular sample. The following review lists the highlights of the DNA typing results obtained by the California Department of Justice DNA Laboratory.
The swatches collected from the blood drops associated with the Bundy trail (leading away from the bodies) yielded only low quantities of human DNA such that only PCR-based testing was conducted. Four such samples were tested and all gave DQA1 and D1S80 results that were consistent with O.J. Simpson's types. Roughly 1 in 500 individuals would have this combination of types. It was also highly significant that the substrate controls (i.e., samplings of unstained areas near the bloodstains) were all negative. The defense's contention that all the stained swatches could be contaminated in the processing of Simpson's reference (liquid) blood would appear to be an extremely remote possibility, since the substrate controls were uncontaminated. Moreover, Cellmark Diagnostics had previously performed RFLP analysis on a larger portion of one of these bloodstained swatches. These results had matched Simpson with a rarity of one in several million. One should bear in mind that these particular samples were collected by LAPD-SID personnel at the Bundy scene prior to the collection of Simpson's liquid blood sample.
Our laboratory also tested three bloodstains that were collected from the rear gate of the Bundy crime scene about three weeks after the murders. All three bloodstains gave PCR test results (DQA1/D1S80) that were consistent with Simpson. RFLP typing was performed on one of these stains. The results of this analysis provided strong evidence that Simpson was the source of this blood. Statistical evaluation of the RFLP pattern indicated that this profile would only be expected in one in several billion individuals. The defense argued that the relatively high quality and quantity of DNA in the gate samples (compared to the condition of the trail bloodstains collected earlier) were cause for suspicion. The prosecution countered that these gate stains were on a different substrate and had been properly preserved. On the other hand, the swatches used to collect the bloodstains on the Bundy walkway had been kept moist in a warm environment that encouraged the growth of micro-organisms. Southern blotting of yield gels followed by hybridization with a human probe provided evidence of this phenomenon in these walkway samples.
Several bloodstains collected from Simpson's Bronco were analyzed. Some of the stains were consistent with Simpson himself. Among the significant findings was a bloodstain from the driver's side carpet that gave PCR results (DQA1/D1S80) consistent with victim Nicole Brown Simpson. This would suggest transfer onto the carpet material from a shoe sole that had walked through her blood on the sidewalk. Another key result was the finding of a mixture consistent with Simpson and victim Ronald Goldman on the center console of the Bronco. There was only a relatively small quantity of blood/DNA to work with and yet the mixture was demonstrated across several RFLP loci (as well as PCR-based loci--which suggested a minor contribution from Nicole Brown Simpson too). The defense sought to keep these results from the jury, arguing that they came in too late. Judge Lance Ito allowed them into evidence. In front of the jury, the defense argued that these bloodstains had been collected long after the incident from a vehicle that had not been properly secured.
With regard to O.J. Simpson's Rockingham residence, the two key items we tested were a bloody right-hand glove found outside Kato Kaelin's quarters by Detective Fuhrman and a bloodstained pair of socks found on the floor of Simpson's bedroom. An additional item from Rockingham consisted of a bloodstain collected from the driveway that gave PCR results (DQA1/D1S80) consistent with Simpson. Three relatively large deposits on the glove gave RFLP results that were consistent with a mixture of Ronald Goldman's and Nicole Brown Simpson's blood. The relative contributions to the mixture varied across these three stains such that one set of bands could be attributed to one victim while the second set went with the second victim. Another area showed an RFLP pattern that was consistent with Goldman alone. An important finding, using the PCR-based D1S80 test, was the presence of DNA from a third person, consistent with O.J. Simpson, in a mixture pattern on three different areas near the wrist.
When initially screened by the LAPD SID Laboratory, no blood was observed on the pair of dark socks collected from Simpson's bedroom. LAPD subsequently gave them a more thorough examination and detected bloodstains on both socks. They tested the largest stain using conventional serological techniques and determined that it was consistent with Nicole Brown Simpson. This was about the time that the news media announced that DNA testing results had implicated the presence of Nicole Brown Simpson's blood on the socks. Both our laboratory and Cellmark tested this bloodstain. These results provided overwhelming evidence that Nicole Brown Simpson was the source of this blood. (Our RFLP results indicated that this profile would only be seen in 1 in several billion individuals.) We were also able to demonstrate that blood consistent with O.J. Simpson himself was present on the upper leg and toe areas of the same sock that had the relatively large deposit indicated to be from Nicole Brown Simpson. The second sock had a series of small spatter-like bloodstains in the ankle region. Two of these were tested using PCR-based tests (DQA1/D1S80) and found to be consistent with Nicole Brown Simpson. This type of pattern argued against the idea that this blood was somehow "planted" on the socks. Clearly, it was difficult to see the blood on the dark background of the socks. In order to document the appearance of the stains, we utilized the expertise and equipment of our Latent Prints Section. Infra-red photography was extremely helpful in providing contrast between the blood and the sock fabric.
In summary, the prosecution used DNA as part of a compelling physical evidence case. The DNA typing results, including those for stains where a mixture of bloods was indicated, were highly significant in terms of forensic reconstruction and association. Based on DNA typing comparisons, several associations, some stronger than others, were established:
Ultimately, however, the case was not decided on the basis of the DNA evidence. It would appear that DNA did play a major role in shaping the defense's strategy. From the opening statement, it was clear that the defense would argue the themes of corruption, contamination and compromise of the evidence. Translated, the defense would contend that bloodstains for which we obtained RFLP results were planted, while significant bloodstains for which we had only PCR results were contaminated in some fashion. Therefore, the defense generally chose to target the LAPD detectives and criminalists rather than the DNA laboratories and their typing results.
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