On Thanksgiving Day in 1984, 14 YO Wendy Jerome left a friend's house and disappeared. For a few hours then her body was found in a school alcove. She had been raped and beaten to death. For 35 years, no one was charged with the crime. Until Familial DNA helped investigators focus on Timothy Williams. His DNA was collected and proved a match for the crime scene DNA obtained from Wendy's corpse.
Familial DNA testing looks for matches that are "close" but not necessarily "exact." Just close enough to indicate that the crime scene DNA tested came from someone closely related to the unknown perpetrator. This helps narrow the suspect list. DNA is then collected from suspects and standard DNA testing looks for a match.
Familial DNA has been involved in many high-profile cases including The Grim Sleeper and the Golden State Killer.
The Golden State Killer:
https://en.wikipedia.org/wiki/Joseph_James_DeAngelo https://abcnews.go.com/US/inside-timeline-crimes-golden-state-killer/story?id=54744307 https://www.grunge.com/245788/how-the-golden-state-killer-was-finally-caught/
