[Expert opinion on biologic stains. Determination of status, future trends].

In this paper an attempt is made to critically review the literature, with special emphasis on bloodstain analysis. One essential aim is the integration of this field into casework. Three basic components in skillful assessment of stains are described: (1) analysis of stain morphology, (2) discriminating and attributing analyses, (3) individualization. Regarding the first, the analysis of stain morphology is based upon the extensive experimental literature published since 1895--mainly in continental Europe. Since 1971 there have also been publications in the American literature. The large family of stain forms and their dependency on multiple variables are described, especially regarding the modes of formation, the energy of impact, and the physical properties of the substrate. The essential elements for reconstruction of the crime are described. The areas of application are arranged in case groups. Since in case work the stain pattern is complicated by many artifacts and overlaps, forensic pathologists are considered the ideal experts for the analysis of bloodstain patterns, as they have a profound knowledge of the type and sequence of injuries. If this is not the case, the forensic pathologist should at least be integrated into the investigating team. In practical application, the stain form is not always adequately analysed. The education and training of pathologists should be improved to achieve this standard. Analysis of the stain morphology and a subsequent selection of stains are also essential prerequisites for meaningful further investigations. By the use of discriminating and attributing analyses, one can as a rule arrive at a definite answer by using only one test. This is true for basic questions such as the identification of blood type, as well as proof of exclusion. One can distinguish between traditional methods, the new field of immunochemistry and rarely used methods. Immunochemistry has permitted success in recent years in determination of the blood group from hair. It is recommended that reference laboratories be established for training in these rare methods. Individualization analyses are subdivided into two large fields: non-DNA individualization and DNA individualization. It is postulated that in the future stain laboratory both areas will coexist. In non-DNA individualization, essential progress has been made. The detection of protein polymorphisms by blotting and subsequent visualization by antibody-linked enzyme/substrate reactions has led to a considerable increase in sensitivity and specificity.(ABSTRACT TRUNCATED AT 400 WORDS)