Developmental Validation of the PrepFiler™ Forensic DNA Extraction Kit for Extraction of Genomic DNA from Biological Samples*

Abstract: The PrepFiler? Forensic DNA Extraction Kit enables isolation of genomic DNA from a variety of biological samples. The kit facilitates reversible binding of DNA with magnetic particles resulting in high DNA recovery from samples with very low and high quantities of biological materials: 0.1 and 40 μL of human blood (donor 2) provided 14 and 2883 ng of DNA, respectively. Following the revised SWGDAM guidelines, performance of the developed method was investigated using different sample types including saliva on swabs, semen stains on cotton fabric, samples exposed to environment, samples with polymerase chain reaction (PCR) inhibitors, blood stains (on denim, cotton cloth, and FTA^® paper), and touch evidence‐type samples. DNA yields for all samples tested were equal or better than those obtained by both phenol–chloroform extraction and commercial kits tested. DNA obtained from these samples was free of detectable PCR inhibitors. Short tandem repeat profiles were complete, conclusive, and devoid of PCR artifacts.     

Comparison of wound patterns in homicide by sharp and blunt force

A comparison of patterns of injuries between sharp force and blunt force homicide was performed. Male predominance was seen in both types of homicides. Most of the victims of sharp force were between 21 and 40 years and those of blunt force between 31 and 40 years. There was no difference in the incidence of victims below 20 years age, but blunt force was almost five times more than sharp force in victims of age above 60 years. Thorax was the commonest site to be involved in sharp force in contrast to head in blunt force. Hand and forearm were the commonest sites of defence injuries in sharp and blunt force homicides, respectively. The majority of the blunt force victims had lesions in only one region in contrast to involvement of 2-4 regions in sharp force. The majority of the victims were killed by acquaintances in blunt force, but criminals always prefer sharp force to kill their victims. Single weapon was more commonly used in blunt force as compared to sharp force. Knife and wooden/iron rods were the weapons of choice in their respective categories. Most of the victims of sharp force were killed outdoor in contrast to victim's own domicile in blunt force.