Laboratory Time and Resources

Time Required to Perform Laboratory Analysis

Step 3: DNA Analysis, Interpretation, cont.

For profiles or portions of profiles that pass quality thresholds, analysts may attempt to ascertain from whom the stain originated. This frequently begins with an assessment of the number of possible contributors to the stain. For profiles from one person (single source), direct comparisons are made to profiles from known individuals associated with the case. If the possible number of contributors is greater than one (a mixture of DNA profiles), a more intricate interpretation procedure is used. Typically, laboratories will attempt to determine if profiles from known individuals associated with the case could have contributed to portions of a mixed stain profile. Interpretation of a DNA mixture can be very time-consuming. The details of this process are beyond the scope of this discussion.

If the interpretation confirms that a known sample in the case could have contributed to the evidentiary stain, a determination of the rarity of the profile is made. In the United States, this is frequently expressed as one in x number of unrelated individuals that would be expected to have the same profile.

Click the image below to view a mixture profile of multiple donors.