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DNA - A Prosecutor’s Practice Notebook Inventory

Cross-Examination Preparation

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National Institute of Justice (NIJ) (see reuse policy).

The foundation for cross-examination begins with the prosecutor's direct examination of the state's DNA analyst. The state's DNA analyst will have already addressed the reliability of the science of DNA, as supported by scientific articles and learned treatises; the propriety of typing; the objectivity of the examiner; and the retention of forensic samples. 

During cross-examination, the prosecutor should obtain concessions from the defense expert witness emphasizing areas in which both the state's DNA analyst and defense experts agree. Typically, the defense experts dispute one or two areas of testing, e.g. database size, leaving other critical areas such as recognition that appropriate controls were utilized and that the controls appear to indicate no problems with the testing.  When this occurs, the prosecutor should highlight these concessions to the jury to underscore that there were no issues with the DNA typing process. 

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