March 26, 2000
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March 26, 2000 |
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Jamaica's DNA Unit
Lloyd Williams, Senior Associate Editor
The following is the first segment of a three-part look at the DNA Unit at the Forensic Science Laboratory. FOR PEOPLE wishing for something positive to cling to, in these days of depressing news from some sections of the public sector, there is a Jamaican agency that can justly and proudly be celebrated. It is the DNA Unit at the Forensic Science Laboratory, 21/2 Hope Boulevard, Kingston 6. But don't take this layman's word for it. Listen to Yvonne E. Cruickshank, Ph.D., director of the Forensic Science Laboratory: "The state-of-the-art system of identification is DNA and we are using flourescence STR Megaplex technology at this time. This is the ultimate technology...state-of-the-art. And we are pleased to say that we are there with them." If you are not familiar with molecular biology, chemistry or biotechnology, DNA talk can be bewildering. The development of DNA or genetic fingerprinting was pioneered in 1984 by the British geneticist Professor Sir Alec Jeffreys of Leicester University, England. The story is that within a three-year period two 15-year-old schoolgirls were raped and murdered in the small English village of Narborough, shocking the community. They disappeared while they were walking home along a country lane. Shortly after the second murder, in 1986, the local police arrested an employee of a local mental institution and he confessed to the second murder, but denied knowing anything about the first. The police, feeling pretty certain that both murders had been committed by the same man, sought a way to establish the guilt of the suspect. Enter Professor Jeffreys, who had discovered that a small piece of DNA that resides in each human being is located on many different chromosomes and may be found in variable numbers at any of these sites. When a person's DNA is examined on a gel, and this specific piece of DNA is detected, the result is a pattern, which is so distinctive that no two individuals, except for identical twins, have the same pattern. Because of the uniqueness of each pattern the technique is called DNA fingerprinting or DNA typing. The police investigating the murder of the schoolgirls, sent forensic samples from the victims and a blood sample from the suspect, to Professor Jeffreys for DNA analysis. His analysis showed that the police were correct and that both girls had been raped and murdered by the same man. But the DNA analysis showed that the assailant's DNA typing was totally different from that of the suspect who had confessed to one of the murders. As a result, the police realizing that the "confession" had been false, released the man from custody and he thus became the first person to be proved innocent by DNA analysis. The police then having the DNA fingerprint of the real assailant, launched the world's first DNA-based manhunt, and requested, voluntarily, a small sample of blood from all the men aged between 18 and 35 years, in the village, resulting in more than 5,000 blood samples being sent to the British Home Office Forensic Laboratories for analysis. The true assailant, Colin Pitchfork, almost escaped the manhunt by getting a friend to give blood in his name. However, the man who substituted for him, was overheard mentioning the switch to his friends while drinking in a pub. The police were notified, and they arrested Mr. Pitchfork and tested his blood which was found to be a a perfect match to the samples obtained from the two murdered schoolgirls. He was convicted and sent to serve two life sentences. Since then, many criminals all over the world have been brought to justice through DNA analysis, and several persons sent to prison for crimes they did not commit have similarly been freed on DNA evidence. At the basis of DNA technology is the fact that each human being has 46 chromosomes, 23 of which are received from each parent. These chromosomes contain the genes which serve as a genetic blueprint to code for the physical characteristics that make each individual different from the other. DNA, for deoxyribonucleic acid, is the chemical that forms the genes and chromosomes. Powerful tool According to the experts on the subject, DNA analysis has become the most powerful investigative tool since the development of fingerprint analysis, as it allows scientists to compare DNA from various biological specimens - saliva, blood, semen, urine, bone marrow, hair and solid tissues - and to identify the donor of the specimen relative to a sample of known origin. The tests involve extracting the DNA from a specimen and dividing it into fragments. Because of the naturally occurring variations in the DNA molecule from individual to individual, the fragments form a pattern that provides an identity profile. This profile can be put to uses ranging from determining the origin of biological specimens left at a crime scene, to resolving disputed paternity of a child. The system Dr. Cruickshank refers to is genetic typing using Polymorphic STR markers which is the state-of-the-art technique for DNA analysis. The DNA Unit "has progressed in STR analysis from silver stain protocols to an automated fluorescently labelled method of analysis to enhance efficiency in throughout." Dr. Cruickshank: "These (genetic) markers are the markers being used by the forensic science community in the United Kingdom, Europe, in the United States and the Caribbean. We are the first in the Caribbean; we are introducing it to the Caribbean." As she explained it, the reason for the 13 "is uniformity, so that we can share our database. In other words, if somebody committed a crime in Jamaica and he went to hide in the U.K. and he jumped a turnstyle or did any kind of thing and was arrested, DNA technology would be able to identify him." She says the DNA Unit started in 1995 with two markers, then moved to seven and now is up to 13. The first criminal case in Jamaica in which DNA analysis was used, occurred several years ago. It was the murder case involving Montegonians Bernard "Damion" Chang, 18, of Westgate Hills; Devon Hill, 22; and Andrew Brown, 20, both of Paradise Crescent, arising from the slaying on September 12, 1995 of Vivene Griffiths, 37, who was manager of Billy Craig Finance & Merchant Bank, Montego Bay. Miss Griffiths's burnt body, with an arm severed, was found on September 13, 1995 at Catherine Pen, near to Rose Heights, Montego Bay. Chang was arrested that evening after police intercepted Miss Griffiths's white Toyota Camry car in which Chang and his friends were travelling along the Rose Hall main road. Brown and Hill were arrested a day later having been implicated by Chang's caution statement. After unshakable DNA evidence was given at the trial in the St. James Circuit Court, Montego Bay, by Dr. Cruickshank, Chang changed his plea from not guilty of capital murder to guilty of non-capital murder. Dr. Cruickshank testified that although Chang and Miss Griffiths had Type A blood, the DNA test using the D1S80 marker and the HNADQ marker (that can differentiate among blood types) established that Miss Griffiths's blood was on a pair of black shoes taken from Chang by the police the night they arrested him. Also, the DNA test located Chang's blood on a pair of brown linen pants belonging to Miss Griffiths and which Chang had left at the house of co-accused Hill. Following Dr. Cruickshank's evidence, Chang's lawyer, Howard Hamilton, Q.C., informed the court that his client wanted to change his plea. The judge sentenced Chang to life imprisonment and to serve 20 years before being eligible for parole. The judge ordered that the accused Hill and Brown be acquitted of the charge of non-capital murder as the only evidence against them was in a caution statement made by Chang ouside of court. The prosecution, conducted by Paula V. Llewellyn, Deputy Director of Public Prosecutions, offered no other evidence against Hill and Brown who both pleaded guilty in the RM Court to larceny. According to Dr. Cruick-shank, since the Bernard Chang case, the DNA Unit had completed more than 1,400 other cases which are in various stages in the court system." "We also have a case where a convicted felon declared that he was not appealing against the murder but he said he did not rape the girl. He asked for his DNA to be done. But I am thinking that it is possible that he might have raped her but he used a condom or didn't discharge and knew that no sperm would be found. But we did it and didn't find any link to him, so he was freed of the rape charge. "So the DNA is a tool for justice, it's not just a tool for conviction." "We are going ahead full speed, we are fully energised. But we are not going to sit on our laurels and think we know it all. We will continue to share with our colleagues around the world. We share things now internationally, regionally and nationally," Dr. Cruickshank said. Tomorrow: DNA demystified |
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