Schiff tried criminal cases as a federal prosecutor in the early days of the DNA-evidence revolution and has continued to be a strong supporter of using DNA technology to its fullest potential to solve crimes. A technology called Familial DNA holds great promise for solving some of the most difficult cases and punishing the guilty. Familial DNA works by matching a sample collected at a crime scene to the database of convicted offenders in such a way that it reports instances where there is a high likelihood that the crime scene sample comes from someone very closely related to a person in the offender database. This technology was used in California to identify and convict the Grim Sleeper serial killer in Los Angeles, an individual who had killed at least 10 people over decades but had gone unapprehended. Using a familial search, which California first authorized in 2009, the police matched DNA from the crime scene to the killer's son, who had been imprisoned for robbery. Further investigation identified the killer, who was arrested and confirmed guilty through additional DNA tests.
Schiff has introduced legislation to authorize the FBI to implement a familial search system for the national DNA database. The legislation includes measures to protect the privacy and civil rights of those in the database, and familial searches would be used only in cases where other leads have been exhausted and only for violent crimes such as murder and rape. Schiff introduced the Utilizing DNA Technology to Solve Cold Cases Act in 2010, and will reintroduce it in the 112th Congress.