The Federal Bureau of Investigation (FBI) Crime Laboratory recently issued a bulletin to National DNA Index System (NDIS) participating laboratories advising them that it had identified errors in the NIST 2013 Short Tandem Repeat (STR) population database. The allele frequencies cited in this publication has been used by many forensic laboratories throughout the country for calculating DNA match statistics. The Vermont Forensic Laboratory (VFL) is one of the many laboratories that had utlized the published data for reporting DNA match estimation statistics since November 2014.
The VFL has taken immediate steps to address the issues identified. The availability of the 2013 NIST STR population data was suspended by the VFL on August 1, 2017 after receiving notification through the CODIS bulletin in July 2017. The VFL has evaluated differences between the 2013 NIST population data and the amended published 2017 NIST population data. Any statistical differences observed were minor and are consistent with the observances outlined in the recent publication (within a factor of two).
Although the number of cases affected by these errors is likely significant, the statistical impact is not. However, statistical calculations for any affected case will be recalculated upon request.
For any questions regarding the notification received by the FBI, impact on previous DNA cases analyzed by the VFL, or the steps taken by our laboratory, please contact the Biology Section Supervisor, Joy Mapp, at 241-5286 or joy.mapp@vermont.gov.