OBJECTIVETo provide a new means for forensic examination of difficult samples including old blood stain, hair (containing hair shafts), decomposed samples and old bone tissues using co-amplification of mitochondrial single nucleotide polymorphisms (SNPs).

METHODSWith Identifiler kit, STR genotyping and 18 mtDNA SNPs (16 SNPs in the coding region and 2 in the control region) detection were carried out using multiple amplification with labeled fluorescence and capillary electrophoresis. The two methods were compared for their performance in forensic caseworks such as old blood stain, cast-off cells, degraded muscles, cartilages, teeth and old bones.

RESULTSThe detection rates of STR and mtDNA SNPs were both beyond 80%, but the latter had a greater success rate. The success rates of mtDNA SNPs were significantly greater than those of STR in the examination of such samples as degraded muscles, cartilages, and old bones.

CONCLUSIONMultiplex amplification of mitochondrial DNA SNPs shows a bright prospect in the examination of difficult forensic samples.