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Abstract: The Hexagon OBTI kit was adapted for human blood detection at crime scenes as well as on items of evidence. The detection limit was increased while its specificity was kept unchanged. The implementation of the kit by the Israel National Police was accomplished with-the introduction of a newly designed "blood testing" carrying case. The case contains all the items and reagents required for the Kastle-Meyer presumptive blood identification test and the Hexagon OBTI test.
Introduction
Currently, crime scene technicians of the Israel National Police (INP) use the Kastle-Meyer (KM) color blood test at crime scenes [1, 2]. This presumptive test gives a strong indication for blood but is not human specific [2]. Following the KM test, the stain is transferred to the laboratory for DNA analysis. In some cases, DNA profiling is not required; however, the investigator must determine whether the stain contains human blood. In these cases, the Precipitin test [2] is performed to determine the source of the stain. Transferring the sample from the crime scene to the laboratory and its analysis is time- and money-consuming.
The Hexagon OBTI test, a commercial kit designed for detection of fecal occult blood [3], was validated by Hochmeister et al. for forensic identification of human blood [4, 5]. The kit consists of a test device and a collection tube. The test procedure is simple and does not require a laboratory setting [3]. The OBTI test is therefore suitable for identification of human blood at crime scenes [4, 5].
This paper reports the results of a validation study carried out for the purpose of implementing the Hexagon OBTI test in the detection of human blood at crime scenes. The Hexagon OBTI kit was included as a component of a new "blood testing" carrying case for crime scene technicians.
Materials and Methods
Body Fluids Stains Preparation
Whole blood samples or blood diluted from human donors and animals were placed on sterile gauze pads and air-dried at room temperature. Diluted blood was prepared by serial dilution in water, and stains were prepared as above.
Animal species tested were orangutan (Pongo pygmaeus), donkey (Equus asinus), camel (Camelus bactrianus), pigeon (Columba livia), chicken (Gallus gallus), cat (Felis catus), dog (Canis familiaris), goat (Capra hircus), sheep (Ovis aries), cow...