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DNA - A Prosecutor’s Practice Notebook Inventory

Lab Tour

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A prosecutor can benefit from touring the lab with the DNA analyst and walk through each step of the procedure which resulted in the lab report. The DNA analyst can explain the purpose and meaning of each document created during the evidence analysis process and the significance of any notes or comments which appear in the report.

Having list of questions in mind may assist the prosecutor with making the lab visit productive. The pretrial consultation enables the prosecutor to review the rules of evidence, courtroom etiquette, and sample defense cross-examination questions with the DNA analyst before going to court. The prosecutor must insure the DNA analyst does not mention the "convicted offenders" database during trial testimony.

List of Questions

1. Does the lab comply with the DAB standards (The National Quality Assurance Standards for DNA labs)?
2. Has the lab been accredited by ASCLD (American Society of Crime Laboratory Directors) or another accreditation body? If not yet, are they in the process? Why is this an important indicator of a high-quality lab?
3. Has the DNA analyst passed all the proficiency testing?
4. Have the population databases been analyzed for Hardy-Weinberg and linkage equilibrium? If so, why is this important?
5. Does the lab handle/process/extract DNA from the evidence and known samples at different times, and in different places? What does the lab do to cleanse the work area after the analysis is completed? Why are these good practices? Is this required by the national standards?
6. Does the lab have a corrective action procedure? What is this, and why is it important? Is there anything in that corrective action file that we should know about/could be used by the defense?
7. Does the lab standard operating procedure differ in any way from that recommended by the manufacturer's user manual?
8. Are the DNA profiles from the evidence "single source" profiles, or is there any evidence of a mixture of DNA from two or more persons? If the case involves a sexual assault, was a differential extraction performed, and, what is the significance of such a procedure?
9. Are all of the DNA profiles "complete" profiles, or are one or more of them a "partial" profile?
10. Is the DNA analyst familiar with the Short Tandem Repeat Interpretation Guidelines, and did he or she follow those guidelines? Is there any possible claim you did not, in any respect, follow the guidelines?
11. Is there any reason to be concerned about "stutter" or "pullup"?
12. Is the DNA analyst prepared to discuss "microvariants," "shoulder," "A peaks," "allelic or locus dropout," "peak height imbalance," "stochastic effect," "amplification inhibitors" as they relate, if at all, to the case?
13. Explain why they called a match?
14. If a mixture is involved, ask the DNA analyst to point out the mixture at each loci.
15. Did the controls all work, and why is that important?
16. What does the DNA analyst do to make sure that no sample mix-up occurs during the process?
17. What charts or graphs might simplify the testimony?
18. What is the DNA analyst's level of certainty as to the results?

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