UK experts fear that proposals to destroy so-called "second swab" DNA samples could slow down investigations if and when the UK moves over to new markers and chemistries. Currently, when a DNA sample is obtained from a suspect, a first swab is used to generate a profile in the NDNAD and a second sample is placed into storage.
Problems could arise when there was a partial match between a crime scene stain processed using the new markers and an old profile in the database generated using six or 10 markers.
Up until now, it would have been possible to re-process the DNA from the second swab, allowing investigators to confirm or deny a match using a comparison based on all the new loci. But soon, that will no longer be an option.