Commonwealth v. Read — Trial ArchiveNicholas Bradford
Testimony Impact
Nicholas Bradford is a DNA analyst employed by BODE Technology, an accredited forensic laboratory. He was called by the prosecution in both trials to present the results of DNA testing performed on a tail light extract and a hair sample recovered from Karen Read's Lexus. His testimony centered on STR (short tandem repeat) mixture analysis establishing that John O'Keefe could not be excluded as a contributor to the tail light DNA mixture, while two Massachusetts State Police troopers — Bukhenik and Proctor — were statistically supported for exclusion.
Challenges & Responses
What attorneys challenged during examination and how the witness responded.
In Trial 2, Alan Jackson cross-examined Bradford on the statistical asymmetry between Proctor's exclusion ratio (76,000 to one) and O'Keefe's inclusion ratio (740 nonillion), eliciting Bradford's acknowledgment that 'strong support for exclusion' is not the same as definitive exclusion. Jackson also highlighted that a number of individuals present the night of O'Keefe's death were never submitted for comparison to the tail light sample. Bradford maintained the accuracy and methodology of his reported findings throughout.
Trial 1 vs Trial 2
In Trial 1, the defense waived cross-examination of Bradford entirely, leaving his statistical conclusions unchallenged. In Trial 2, Alan Jackson conducted a substantive cross focused on two points: pressing Bradford on the distinction between statistical exclusion and absolute exclusion for Proctor, and establishing that numerous individuals from the Albert household had never been compared to the tail light DNA sample. The cross did not undermine the O'Keefe inclusion statistic but framed the exclusion of other potential contributors as incomplete.
Notable Quotes From The Record
“So in this case, when comparing the John O'Keefe profile, assuming a mixture of three individuals, it is at least 740 nonillion times more likely to be observed if it originated from John O'Keefe and two unknown unrelated individuals than if from three unknown unrelated individuals.”
The central finding — overwhelming statistical support for O'Keefe's DNA on the tail light
“That would be the number with 30 zeros.”
Puts the statistical weight in plain terms for the jury
“So that sounds confusing given what I just said. So the verbal qualifier for that would be very strong support for exclusion.”
Excludes Trooper Bukhenik from the tail light DNA mixture, addressing contamination concerns
“We quantified the hair and it was below the limit of detection, so we did not process that hair forward for STR.”
Explains why the hair sample required different (mitochondrial) testing by a different analyst
“John O'Keefe could not be excluded as a potential contributor to that mixture profile.”
Reports Bradford's conclusion that O'Keefe could not be excluded as a potential contributor to the tail light mixture.
“it would be 740 nonillion times more likely that it was a mixture of John O'Keefe and two unrelated individuals versus three unknown unrelated individuals.”
Reports the likelihood ratio for O'Keefe and two unknown unrelated individuals versus three unknown unrelated individuals.
“So he could not be visually excluded based on just comparing the profile to the STRmix output. So we do the likelihood ratio... So in this case it was 46 million times more likely that it was three unknown unrelated individuals versus Yuri Bukhenik and two unknown unrelated individuals. So that would be very strong support for exclusion.”
Reports Bradford's testimony that Bukhenik was not visually excluded on the initial comparison, followed by a likelihood ratio providing very strong support for exclusion.
“the quantification results were below the limit of detection. So we would not expect to get an STR profile from that hair.”
Explains why the hair evidence required different (mitochondrial) DNA testing by another analyst.
“So, like I said, in this case, it's 76,000 times more likely that we would observe that evidence profile if it were three unknown unrelated individuals as opposed to Michael Proctor and then two unknown unrelated individuals.”
Bradford framed the 76,000 statistic as a comparison between two explanations of the evidence profile, rather than a population analogy.
Key Moments
- Bradford's central finding — that the DNA mixture on the tail light was 740 nonillion times more likely if John O'Keefe were a contributor than if three unknown individuals contributed — became one of the prosecution's most powerful statistical assertions, with Bradford explaining for the jury that a nonillion is a number with 30 zeros.
- Bradford excluded Trooper Yuri Bukhenik from the tail light DNA mixture with a likelihood ratio of 46 million to one in favor of exclusion, directly addressing defense concerns about contamination during evidence handling.
- Regarding the hair sample recovered from the vehicle, Bradford testified that the DNA quantity was below the limit of detection for autosomal STR testing, explaining why a different analyst performed mitochondrial DNA analysis on the hair — a distinction Bradford walked through carefully for the jury.
- On cross-examination in Trial 2, Bradford acknowledged that Trooper Michael Proctor's exclusion from the tail light mixture carried a likelihood ratio of 76,000 to one — statistically significant but orders of magnitude weaker than the nonillion-scale support for O'Keefe's inclusion — and that several other individuals had never been compared to the sample at all.