Encoded evidence: DNA in forensic analysis

DNA varies between and within species, and so it can be used in forensic work when biological material is associated with a crime or other legal case.Forensic DNA analysis began in 1985 with the development of DNA fingerprinting; most analysis is now carried out with PCR multiplexes of 10–15 autosomal STRs that give a high degree of certainty in individual identification.Many circumstances, including mixtures of DNA from more than one donor, can give rise to anomalous profiles, but these can usually be resolved.Semi-automation of DNA profiling allows the construction of large databases of profiles from suspects, offenders and crime-scene samples; the rules for creating and maintaining these differ from country to country.Analysis of autosomal SNPs, Y chromosome haplotypes and mitochondrial DNA sequence variation are also useful in specific applications.DNA profiling can provide some information about the population of origin of a sample, although direct prediction of phenotypic features is more problematic.The identification of victims of wars, disasters and accidents are greatly facilitated by sensitive DNA profiling methods.Analysis of the DNA of animals, plants and micro-organisms associated with legal cases can provide valuable evidence.