Criminal intelligence databases and interpretation of STRs

DNA profiling in forensic science in the UK is focussed on the analysis of short tandem repeat (STR) loci using PCR. It is the technique of choice for the national strategy to create criminal intelligence databases. Apart from the increased sensitivity inherent with any PCR technique, with STRs there is also the advantage of definitive allelic identification. This is a consequence of lower measurement errors associated with the use of Polyacrylamide gel electrophoresis to detect DNA fragments ranging between 200–400bp in size (Ziegle et al. 1992).Because of their small sizes STRs are more likely to be successful on old or badly degraded material (Gill et al. 1994; Hagelberg et al. 1991; Jeffreys et al. 1992; Weigand et al. 1993) an important aspect of forensic casework.