Court of Appeals Rejects Challenges to Y-STR DNA

In People v. Wood, the Court affirmed the trial court’s admission of Y-STR DNA testing to isolate the male Y-chromosome DNA on a scarf used to bind the victim’s hands.  The scarf contained DNA from four individuals, only one of which was a man.  The Court recognized that Y-STR DNA testing is an accepted practice, and held that the method’s limitations go to the weight rather than the admissibility of the evidence. The Defendant (and a co-defendant) had broken into

The Defendant raised a Daubert challenge to the Court’s decision to admit the DNA evidence from a scarf used to bind the victim’s hands. Because the scarf contained DNA from at least four people (only one of whom was male) the forensic analyst used the Y-STR method of DNA testing to isolate the male Y-chromosome DNA.

Unlike more common STR DNA testing, which can identify a unique individual, Y-STR DNA testing cannot because a man will have the same Y-STR DNA profile as his father and grandfather, and because random matches in the general population are also possible. Stated another way, Y-STR is significantly less reliable to than STR testing.

Since the forensic analyst testified in detail about the limitations of Y-STR DNA evidence, and Y-STR DNA testing is an accepted practice, the court held that the method’s limitations go to the weight rather than the admissibility of the evidence and it was properly admitted.
 
The Court of Appeals also rejected the Defense 404(b) challenge and the defense prosecutorial misconduct challenge.
People v Woods, Court of Appeals No. 315379.