Say they found DNA @ the 7 Bridges discovery - if there is no DNA record on file to match it with, LE does not know who it belongs to.
The National DNA Index System
Q: What is the National DNA Index System or NDIS?
A: NDIS is the acronym for the National DNA Index System and is one part of CODISthe national levelcontaining the DNA profiles contributed by federal, state, and local participating forensic laboratories. NDIS was implemented in October 1998. All 50 states, the District of Columbia, the federal government, the U.S. Army Criminal Investigation Laboratory, and Puerto Rico participate in NDIS.
The DNA Identification Act of 1994 (42 U.S.C. §14132) authorized the establishment of this National DNA Index. The DNA Act specifies the categories of data that may be maintained in NDIS (convicted offenders, arrestees, legal, detainees, forensic (casework), unidentified human remains, missing persons and relatives of missing persons) as well as requirements for participating laboratories relating to quality assurance, privacy and expungement.
Once a suspect has been identified, investigators seek to legally obtain a DNA sample from the suspect. This suspect DNA profile is then compared to the sample found at the crime scene, in accordance with well established and constitutionally accepted practices, to definitively identify the suspect as the source of the crime scene DNA
FBI agents cannot legally store DNA of a person who was not convicted of a crime. DNA collected from a suspect who was not later convicted must be disposed of
and not entered into the database.
http://www.fbi.gov/about-us/lab/biometric-analysis/codis/codis-and-ndis-fact-sheet