Double swab technique for collecting touched evidence.
Touched evidence is often submitted to forensic laboratories for DNA analysis. Classical stain recovery technique, involving one wet cotton swab, is commonly used for recovering the touched evidence. Double swab technique, using a wet cotton swab followed by a dry cotton swab, was compared with the classical technique for recovering the touched evidence. The wet cotton swabs and the dry cotton swabs were individually extracted. DNA extracts were quantified and amplified at 15 polymorphic loci. DNA recovered in some of the second dry swabs contained sufficient amount of DNA to yield a DNA profile. This study shows that the double swab technique improves the quality of the resulting DNA profiles. The double swab technique for recovering touched evidence at crime scenes is recommended.
Pang
B C M
BC
Forensic Science Division, Hong Kong Government Laboratory, Homantin Government Offices, 88 Chung Hau Street, Kowloon, Hong Kong SAR, China. cmpang@govtlab.gov.hk
Cheung
B K K
BK
D000483:Alleles; D003415:Crime; D016172:DNA Fingerprinting; D005554:Forensic Medicine; D006801:Humans; D018895:Microsatellite Repeats; D016133:Polymerase Chain Reaction; D013048:Specimen Handling / Q000379:methods*