Investigative Genetic Genealogy (IGG) has revolutionized forensic investigations by helping to identify unknown individuals—whether they are suspects in violent crimes or unidentified human remains. Below are some of the most common questions about IGG and how it works. How does investigative genetic genealogy work? IGG uses DNA from a crime scene or unidentified remains and compares it to DNA databases that allow law enforcement access. By analyzing genetic matches, genealogists build family trees to identify potential relatives, which can lead to the identification of a suspect or an unidentified person.