DNA Casework & Forensic Serology

DDC employs presumptive and confirmatory tests that detect the presence of blood, semen, and saliva on evidence or unknown samples. When sources of human DNA are identified, our forensic DNA analysts extract the DNA for testing and analysis. Depending on the sample type and condition, one or more of the following testing systems may be used:

• STR “Short Tandem Repeat” typing using the 15 core CODIS markers plus 9 additional markers. This is the most commonly used and most powerful of the testing systems. The profile generated is unique to each individual and is regularly used for all types of biological samples.
• Y-chromosome STR typing of 27 markers that are male specific, paternally inherited, and therefore not unique to an individual. Y-STR testing is often used in samples containing a mixture of male and female DNA where the two cannot be separated, as in sexual assault cases.

Compare DNA Profiles to Reference Standards  

When DNA from evidence has been analyzed, the DNA profile can be used to compare to DNA from a reference standard of the suspect or victim.

DNA evidence can also be used to prove the innocence of a falsely-accused or wrongly- convicted person, as well as identify the bodies of victims of violent crimes, accidents, or natural disasters. The power of DNA technology in identifying individuals and establishing biological relationships makes its applications limitless.