Facts
- Rashon Pike was charged with armed robbery by firearm arising out of a robbery in which two victims later identified Pike as being involved.
- The State linked a handgun to the robbery and collected swab samples from the gun for DNA testing.
- The State called forensic scientist Lisa Fallara, who testified about Y-chromosome short tandem repeat (Y-STR) testing, a method that examines locations on the male Y chromosome and can be used when only a small amount of DNA is available.
- Fallara reported the swabs contained a mixture of DNA from at least two males.
- Comparing the mixture to Pike’s known DNA profile, Fallara testified Pike could not be excluded as a contributor, but she could not identify him as the contributor.
- Fallara also testified that the Y-STR profile from the gun was consistent with about one in every two Black males, Caucasian males, and Hispanic males—meaning roughly 50% of males could have contributed to the mixture, and Pike was within that group.
- Pike did not object at trial to the admission of Fallara’s “one in two” probability-of-inclusion statistic.
- The jury convicted Pike, and he appealed.
Issues
- Whether expert testimony that a mixed Y-STR profile was consistent with approximately one out of two males (a “50% probability of inclusion”) was relevant to the disputed issue of identity, and if irrelevant, whether its admission warranted reversal under plain-error review.
Decision
- The court held the “50% probability of inclusion” Y-STR statistic was admitted in error because it was irrelevant to proving Pike’s identity; it did not make it more likely than not that Pike was the perpetrator.
- The court nevertheless affirmed the conviction, concluding the unpreserved evidentiary error did not amount to reversible plain error.
Legal Principles
- Evidence is relevant only if it tends to make a material fact more or less probable; evidence that does not meaningfully change the likelihood of a fact in dispute should be excluded.
- DNA testimony may be presented through statistics, but a statistic that includes an extremely large portion of the population (e.g., about 50% of males) may have no real tendency to prove the defendant’s identity in a criminal case.
- When a defendant fails to object at trial, review of an evidentiary claim is generally forfeited and may be considered only under the plain-error doctrine.
- Under plain-error review, reversal is reserved for limited situations, such as when the evidence is closely balanced or when the error is so serious that it affected the fairness of the trial and the integrity of the judicial process.
Conclusion
People v. Pike held that admitting Y-STR evidence stating Pike could not be excluded from a mixed profile shared by roughly half of the male population was irrelevant to identity and therefore erroneous, but the error did not justify reversal on plain-error review, so Pike’s conviction was affirmed.