Forensic Science and Police Work Forensic science has been playing a very crucial role in crime-solving activities of the investigative agencies for last many years. Its popularity has grown tremendously even though it cannot be trusted to formally indict someone. This is because while forensic evidence is considered important, there are certain specific problems attached with it, which can significantly limit the credibility of the results obtained from forensic examination.

Forensic evidence refers to detailed analysis of things found at the crime scene including apparently vague and elusive pieces of evidence such as hair, fingerprints, body fluids, handwriting etc. After thorough analysis of such evidence, the forensic scientist can at least find some clues to who might be the offender but usually they are not sufficient to bring indictment or charges against one particular suspect. This is why not everyone is in favor of forensic evidence as there are several problems connected with achievement of accurate results through forensic testing. For example, even though DNA matching is the most respected of all forensic techniques, it cannot link presence of a person in a room with the crime that took place there. (Udall, 1990)

Police has been using forensic science for decades now, but repeated blows against its credibility are to likely to its progress in future. For example, even though DNA analysis is one the most popular techniques being used by police but even this sophisticated methodology can give misleading results. World-renowned forensic scientist Dr. Henry Lee offers insight into why DNA evidence may not yield any answers at all in some cases, and why police cannot always depend on DNA samples to identify the offender. Dr. Lee explains, "Sometime DNA evidence you found is not important at all. When two objects have 'contact', you have transfer. The car hit the pedestrian. You get transfer. That's how we solve hit-and-run case. If somebody touches something, now you are going to have transfer. If you move this object, put in a different location, you pick up more, deposit some, then you move another location, you pick up and deposit, the whole pattern changed." (ABC Good Morning America, 03-13-1997)

However, with all its disadvantages and problems, Forensic science is being widely used by police agencies to solve crimes mostly the serious ones such as homicide, rape and kidnapping. It is important to remember that forensic science appeared on the scene of police work back in early 1900s when fingerprinting gained popularity and was considered first forensic evidence to aid police investigations. Dr. Henry P. DeForrest is known as the pioneer of fingerprinting in the United States and New York State Prison system adopted it for investigation work in 1903. (Easterbrook, 2000)

Though forensic science has been aiding police work for a long time, it is only in the last two decades that it gained any real prominence. With better technologies being adopted by police departments worldwide, forensic evidence stands a better chance of entering formal investigations. But while these technologies have helped accentuate the significance of forensic science, they have also played a dominant role in discrediting forensic evidence. For example finger printing which is the oldest form of forensic evidence is widely being considered part of junk science that should be kept out of the court. Similarly no case involving DNA matching as primary evidence has ever made it to the Supreme Court in the United States.

Fingerprinting gained popularity in police investigations when Identification Division of the F.B.I was setup in 1924. After that finger printing technique gained importance in police work and by 1946, the F.B.I. had processed 100 million fingerprint cards and by 1972 the number had increased to 200 million cards. But all these files were manually maintained because of slow technological advancement. AFIS technology however changed the scene and fingerprinting came out of its primitive stage and FBI had computerized fingerprinting records of more than 33 million criminals. (Murphy, 1996)

Fingerprinting is the oldest and by far the most commonly used forensic technique by police agencies nationwide. This system has been aiding police work for last 100 years now. With advancement in technology however, fingerprinting has also encountered criticism. It is felt that poor computerized images of prints lead to errors and mismatches and therefore prints cannot be trusted completely. To rectify this problem New York police department is testing a new technology called 'live scan'. In this technique, prints of an offender are placed on a glass plate and fed into a computer. This data is later shifted to main computers for matching.

In Daubert v. Merrell Dow Pharmaceuticals court made it clear that only a technique which is 'subject to peer review, possesses known rates of error, and is generally accepted as science' can be allowed as evidence during trials. However critics feel fingerprinting doesn't satisfy these conditions and thus cannot be depended upon during police investigations.
Adrian Cho (2002) writes, "[On January 7, 2002], Judge Louis H. Pollak of the U.S. District Court for the Eastern District of Pennsylvania found that fingerprinting fails three of the four Daubert standards. Pollak, a former dean at the University of Pennsylvania and Yale law schools, ruled on whether fingerprint evidence could be introduced in a trial in his court. He rejected the argument that the technique had been tested both by nearly 100 years of courtroom experience and by examiners checking each other's findings. Fingerprint identification also has not been subject to peer review, he found, in part because fingerprint examiners do not constitute a "scientific community." The judge further found that the rate at which practitioners make errors has not been quantified."

Fingerprinting is only one part of forensic science but it is the technique, which made use of forensic science popular in police work. Its involvement in police work and its rejection as a scientific technique says volumes about forensic science in general and its significance in police investigations. Contamination is the main problem in forensic evidence and this is what often discredits it as sound proof in U.S. courts.

Over the last fifty years, forensic science has undoubtedly helped police in criminal investigations in hundreds of ways. Though it has never been used to identify murderers, it has definitely helped in narrowing down the focus of investigation by providing valuable clues to actual offenders. Forensic evidence and its rigorous testing can lead to valuable information though results cannot be termed as conclusive. Its significance is evident from the fact that since 1990, forensic evidence in U.S. police laboratories has grown some 23%. This makes it clear that law enforcement agencies are indeed making wide use of forensic science to track down offenders. (congressional Testimony, 2001)

DNA revolution has been the greatest milestone in the history of forensic science and its involvement in police work. Where previously forensic evidence couldn't be used to convict or acquit a person, countries all over the world are actively using DNA samples and genetic matching to achieve the same. For example, Ronald Keith Williamson was released in 1999 after ten years of imprisonment. He had been indicted on rape and murder charges of one Debra Sue Carter in Ada, Oklahoma. DNA testing however revealed no link between the accused and the forensic evidence that had been gathered by police from the crime scene. (Barry Scheck and Peter Neufeld, 2001)

The reason forensic science especially the latest technologies including DNA matching is important is evident from the fact that in the year 2000, some 68 alleged criminals imprisoned in federal and state courts were declared innocent. Some of them were on a death row too and their innocence proven through DNA testing led to public outrage. In English where DNA fingerprinting was invented, some 70,000 cases have so far been solved through this technique. (Easterbrook, 2000) Therefore we cannot deny the fact that the role of forensic science in police work has increased over the last fifty years especially after the invention of DNA identification system.

In early 1980s, English geneticist Alec Jeffreys learned that markers on human chromosome were unique in every person except for twins and thus developed a system where these short structural areas were translated into barcodes. Andrew Watson (2000) sheds light on use of DNA identification in its primitive stages, "His [Jeffreys] approach, called multilocus profiling, used restriction enzymes to cleave the DNA at specific sites. The resulting fragments differ in size from person to person, as revealed by gel electrophoresis, in which fragments of different masses migrate at different speeds when subjected to the pull of an electric field. That was 1985, when a single, relatively large specimen took weeks to process and yielded a barcode like output that was difficult to compare to other DNA samples."

Over the years however law enforcement agencies realized the importance of DNA identification in police work but found the barcode system a little too complicated and lengthy. This led to the development of short tandem repeat (STR) technique in…