I received a CODIS hit letter. The letter indicates I need to get a search warrant to collect a known DNA sample from the listed individual. Why do I need another DNA sample?

Offender samples used by the DNA offender database do not have an associated chain of custody and are generally inadmissible in court.  In order for the DNA evidence to be presented in court, an additional DNA report needs to be issued. A new known DNA sample with documented chain of custody is needed for this report in order to perform a direct comparison between the individual listed in the CODIS hit letter and the DNA profile obtained from the crime scene evidence.  In addition, no statistical analysis, which is a required component of DNA reports, can be performed without a known DNA sample that has a properly documented chain of custody.