In 1992, an 84-year-old grandmother was brutally assaulted and killed in California. For 25 years, the mystery of her death went unsolved — and her killer unapprehended — due to the lack of physical evidence to tie him to the crime. Twenty-five years later, police paid a visit to a pizza party where they found sufficient evidence to arrest her murder. At first glance, the murder and the pizza party seem unrelated. However, there is a link: familial DNA…