Struggling to wrest helpful testimony out of an experienced prosecution witness - and hampered by tough rulings from Superior Court Judge Lance A. Ito - a lawyer for O.J. Simpson focused Monday on the error rates of the laboratories that collected and tested evidence in the murder case.
Peter Neufeld, one of Simpson’s DNA legal experts, spent much of the day grilling Cellmark Diagnostics director Robin Cotton about possible problems with the testing in the Simpson case, by posing questions about the statistical basis for describing the significance of DNA “matches” and by attempting to elicit her criticisms of the handling of evidence by the Los Angeles Police Department.
Neufeld suggested that Cellmark’s database used to make assertions about the rarity of various genetic markers is woefully small, and he reminded jurors that Cellmark had made at least two mistakes in proficiency tests - errors that the defense lawyer attempted to emphasize by confronting Cotton with the tests and displaying them for the jury. A prosecutor later responded by noting that the mistakes occurred in the late 1980s and by eliciting Cotton’s testimony that the lab has not produced incorrect results in proficiency tests since 1990.
The themes advanced Monday by Neufeld - of laboratory error and evidencecontamination - are at the heart of the defense’s attempt to rebut the DNA evidence suggesting Simpson’s guilt in the June 12 murders of his ex-wife, Nicole Brown Simpson and her friend, Ronald Lyle Goldman. Simpson has pleaded not guilty to those killings, but his legal team is confronted with an array of DNA evidence that prosecutors say links Simpson to the crimes.
In a series of startling disclosures last week, Cotton told the jury that only one of 170 million people could be expected to have the genetic markers found in a blood drop near the bodies of the victims. Simpson’s blood was consistent with that drop, she said.
And the blood on a sock discovered in Simpson’s bedroom only could have come from about one person in 6.8 billion.
Neufeld began the defense response last week, and he continued it Monday with an approach that in some ways mirrored the prosecution’s presentation. Neufeld on Monday projected slides of grainy black-and-white X-ray films that appeared to match. Unlike prosecutors, however, Neufeld then elicited Cotton’s admission that those tests portrayed by the X-rays had produced false results.