[Stain examination with DNA technology--a retrospective analysis].

The extended possibilities of forensic stain analyses during recent years have mainly resulted from the application of DNA technology. Among the VNTR polymorphisms, one can differentiate between five consecutive generations of systems, i.e. multi locus systems (MLS), single locus systems (SLS), so-called AMPFLP's (amplificable fragment length polymorphisms), short tandem repeats (STR's), micro satellite systems. The routine application in our laboratory lets us distinguish 3 phases: (I) RFLP phase (MLS+SLS); (II) combined application of RFLP-SLS and AMPFLP's; (III) PCR phase (combined application of AMPFLP's and STR's.--Investigations applying conventional blood group systems and RFLP analysis have been cancelled in phase III. Since 1989 328 cases have been investigated. The number of cases per year was doubled in phase III compared to phase I, but the proportion of DNA determination has been increased by app. 800%. Although in phase III the stain material was on average more degraded and quantitatively smaller the application of STR systems was successful in 90% of all cases and therefore much more effective than other systems. Compared to phase I, the probabilities of inclusion were smaller in phase III. Problematic stains were more often investigated. Also, a strategic change has occurred. New standards had to be elaborated, i.e. to the avoidance of contamination, to the critical evaluation of stain composition and to the validation of systems.