DNA evidence collection and forensic analysis in criminal justice

DNA in Criminal Justice System

DNA in the Criminal Justice System -- DNA as Evidence

Justice and Science

Sources of DNA at Crime Scene

Evidence Collection

DNA Evidence on Trial

DNA Matching

This paper addresses the use of DNA in criminal justice system. The research paper will cover the usage of DNA as evidence. The importance of DNA in any criminal case as forensic evidence will be discussed through case studies. The role of DNA in court rooms will also be discussed and it will also cover the role of DNA in making a case stronger for the victim. Advantages and disadvantages of DNA as evidence and DNA testing are also discussed in the paper.

DNA stands for deoxyribonucleic acid. It is considered as one of the building blocks of the human body because it is present in the nuclei of the cell. Genes are the hereditary material of human beings present in their DNA. Estimated amount of genes in a human body is 20,000 to 25,000 genes. Every human has two copies of every gene, one of which is inherited from parents. Less than 1% of the total number of genes is marginally different between every human being; which forms the basis of DNA analysis and parenting tests. Due to the uniqueness of DNA, it is very useful if examined at a crime scene. The two common methods for identifying and describing DNA Are Restriction fragment polymorphism (RFLP) and STR i.e. Short tandem repeat profiling (Dr. Mandal, 2012). In this paper we will discuss the use of DNA as evidence; its significance and essentiality

Justice and Science

Fingerprints were considered to be the most important tool for law enforcement. But the use of fingerprints is in few cases in which the criminal leaves prints on the crime scene. There were other tests used for investigation like hypnosis, voiceprints and gunpowder residue on gun. But now, the science has helped the judicial system to ensure complete surety about crimes through DNA in many cases (Clarke, 2007).

Sources of DNA at Crime Scene

There are many sources of DNA at a crime scene. Blood found on clothing items can be easily processed in the laboratory. Properly preserved semen can be an excellent source of DNA. Clothing items and hair are also a source of DNA (Gahn, 2005). All of these sources are valuable only if they are preserved properly and shipped to the testing lab safely.

Evidence Collection

Collection of evidence is a very critical matter. Law enforcement personnel should to be very careful while collecting evidence from a crime scene. Valuable DNA evidence can be found throughout the crime scene like biological matter on clothes, door knobs and sheets. If these evidence items are collected and stored prudently, then they can be tested for DNA and could prove valuable for the trial. Heat, humidity sunlight and bacteria can degrade DNA very quickly therefore it is very essential to take necessary precautions while collecting DNA. Potential DNA evidence should be stored in paper bags rather than plastic bags. Properly stored evidence have had yielded much better results in the court rooms (Gahn, 2005).

DNA Evidence on Trial

In 1987, the first DNA testing was done on a double rape and murder in Narborough, England. Initially the DNA test ruled out the initial suspect, Colin Pitchfork because he switched blood samples with his friend. But someone heard the friend talk about the switch and original blood sample of Colin was tested and hence he was proven guilty (Cohen, 2003). DNA testing has improved a lot over the 20 years but still mistakes can be made which can mislead the trial. American Society of Crime Laboratory Accreditation on Board in Garner, NC says that 4240 out of 400 to 500 labs are fully equipped with DNA testing but 25 are still seeking accreditation (Briody, 2004).

In Hanover Park case, DNA of Steven B. Sower was used to prove him guilty of sexual assault of a 10-year-old girl outside Glendale Heights elementary School in July. In another case, in Naperville, police used the DNA to charge Richard g. Hess Jr. with murder and aggravated criminal sexual assault of a 23-year-old Nicole Kornely in December 1995 (Cole, 1997). The DNA evidence in these cases is easier to find if the victim is alive or the body is found after the murder. Cole (1997) states, that FBI began DNA testing for trails in 1988. There have been 12,000 cases reported since then till 1997. However, FBI pointed out that out of these 12,000, almost a quarter of the suspects in these cases was exonerated. Till 1997, DNA examiners have testified in about 600 trials for DNA as evidence to prove the suspect guilty.

Jury is a very essential part of any trial. If the jury is aware of the importance of DNA, then it has greater chances of a fair trial. An expert presentation should be given to the jury in the trials which contains DNA evidence. The understanding of DNA by juror enhances their knowledge. Strong DNA evidence also increases the conviction rate of a trial. In Australian trials, six topics were covered in jury presentation about DNA. These topics were structure of DNA, alleles and its measurements, laboratory processing of DNA, profile interpretation; random probability match and its significance and DNA match (Goodman-Delahunty & Hewson, 2012). The scientific opinion on DNA can only be given by a scientific person with specified knowledge and training. This can ensure the fair trial (Gans & Urbas,, 2002).

Conclusion

DNA as evidence preserves time and leads the investigation towards the right direction. It prevents the investigators to investigate a wrong person. It is also cost effective and creates a link between crime and suspect which could eventually lead to the conviction and punishment of the criminal. Many innocent convicted people have been brought to justice only due to the presence of DNA testing or DNA matching at some other crime scene or late display of evidence. However, there is always a chance of evidence tempering when DNA is involved as evidence. Extensive use of DNA as evidence in Australia and USA has led to unquantifiable cost and reduction of person's privacy as well as individual's freedom (Gans & Urbas,, 2002). There are sometimes wrong or misleading results from the DNA testing but it cannot prevent the extensive usage of DNA as evidence.

We can conclude that despite all disadvantages and complication. DNA has proved to be a very efficient and essential in many trials. It is one of the reliable forensic evidence that has brought justice to wrongly suspected or convicted people. If DNA is preserved in a proper way and is not tempered with, then it can be the main evidence which can solve cases like murder, abduction and rape. It is one of the best tools to identify the body. Thus, improving the quality of DNA testing and presenting it in a way the even a layman can understand it, will lead to more fair trials and bring justice to the victims.