DNA testing of sexual assault cases: Surmounting challenges in the Philippine setting

In the Philippines, conviction of sexual offenders mostly relies on testimonial evidence provided by the victim or the victim’s family, which may be prone to bias, subjectivity and fraud. Many cases involve child victims who are very young and are likely to be scared of informing others about the abuse.

DNA analysis provides the most powerful tool for human identification and has been in the Philippines since the late 1990s. Unfortunately, DNA testing has not been used routinely. The failure to properly collect, store and analyze biological samples had prolonged the suffering of a victim and her family. Moreover, other crimes could have been prevented had the real perpetrator been identified and incarcerated.

Because of the close, physical contact between victim and offender during an assault, biological material from the assailant is almost always left on the victim’s body. DNA collected from cases of sexual assault is usually in the form of mixtures, with the offender’s (or offenders’ as in the case of gang rape) DNA commingling with the victim’s DNA. If not properly handled and stored, DNA obtained may be degraded faster due to the tropical and humid environment in the country. A highly robust system for DNA testing of sexual assault cases from collection, handling, laboratory analysis and storage, is therefore necessary.

The DNA Analysis Laboratory, Natural Sciences Research Institute (www.dnaforensic.org) in UP Diliman, together with the Institute of Biological Sciences, UP Los Baños (ibs.uplb.edu.ph), is undertaking a research project that entails the validation of procedures for sample collection, processing and DNA analysis of biological samples commonly collected from a victim using a sexual assault investigation kit (SAIK). It is hoped that the study will be used to form guidelines for handling this type of evidence in order to accelerate the fair administration of justice by Philippine courts.

Generally, evidence materials such as vaginal swabs have to be collected within 72 hours from the time of the last contact. During collection, it is imperative that procedures, e.g. use of sterile materials and proper laboratory gear, must be in place to avoid contamination. Appropriate storage conditions, must also be maintained to prevent bacterial and fungal growth which damage the DNA. Proper chain of custody should be observed to avoid tampering or loss of evidence.

Second, the type of DNA markers to be used in analysis has to be properly chosen for their appropriateness in answering issues raised in court and their degree of polymorphism needed for effective individuation of persons. The most commonly used markers are the male-specific Y-chromosomal short tandem repeats (Y-STRs) because many perpetrators are males. Another set of markers are autosomal STRs (aSTRs), which are valuable in the direct determination of a person’s parents.

To make DNA testing routine, one of the greatest challenges is to bridge the gulf that separates scientific discovery generated by university researchers and the relevant sectors in Philippine society. Hence, one of the commitments of the UP-NSRI DNA Analysis Laboratory is to disseminate relevant information to government authorities and local communities through lectures and published works. The collective efforts for research and extension being conducted at the laboratory have the ultimate goal of augmenting the national capacity for forensic DNA technology. When science, such as DNA testing, is placed at the service of society, our courts’ mandate to convict the guilty, to free the innocent, and to give justice to the victim, is more effectively fulfilled for the good of all.

* * *

JJRB Rodriguez is a BS Biology cum laude graduate from UP Los Baños. He is currently working on the research entitled “Formulation of an Integrated System of Forensic DNA Testing for the Evaluation of Sexual Assault Cases in the Philippines” at the DNA Analysis Laboratory, Natural Sciences Research Institute in UP Diliman, as part of his Master of Science in Genetics degree at UP Los Baños. In 2012, he presented part of this work at the Asian Forensic Science Network (AFSN) in Bangkok, Thailand. He has been teaching genetics and cell biology at the Institute of Biological Sciences, UP Los Baños since 2007.

Dr. RP Laude is a professor of Genetics at the Genetics and Molecular Biology Division, Institute of Biological Sciences, UP Los Baños. She is currently the program director for Agriculture of the Philippine Genome Center of the University of the Philippines System.

Dr. MCA de Ungria is the head of the DNA Analysis Laboratory, Natural Sciences Research Institute of UP Diliman and has appeared as expert witness in cases involving disputed parentage issues and in relation to criminal cases. The UP-NSRI DNA Laboratory continues to offer its parentage testing and DNA profiling expertise as part of its commitment to serve the community. The laboratory may be contacted at 632 925-2965 and [email protected].