DNA in Criminal Cases - Solving Cold Cases in California with Forensic Science
This research will attempt to analyze and discuss the feasibility of DNA testing in solving cold cases and will study the impact that DNA fingerprinting has had on the forensic science community as a whole.
DNA is generally used to solve crimes in one of two ways. In cases where a suspect is identified, a sample of that person's DNA can be compared to evidence from the crime scene. Crime scene evidence can also be linked to other crime scenes through the use of DNA databases. DNA evidence is generally linked to DNA offender profiles through DNA databases. In the late 1980's, the federal government laid the groundwork for a system of national, state, and local DNA databases for the storage and exchange of DNA profiles. This system, called the Combined DNA Index System (CODIS), maintains DNA profiles obtained under the federal, state, and local systems in a set of databases that are available to law enforcement agencies across the country for law enforcement purposes. CODIS can compare crime scene evidence to a database of DNA profiles obtained from convicted offenders. CODIS can also link DNA evidence obtained from different crime scenes, thereby identifying serial criminals. (Lee)
When properly documented, collected, and stored, biological evidence can be analyzed to produce a reliable DNA profile years, even decades, after it is collected. Just as evidence collected from a crime that occurred yesterday can be analyzed for DNA, today evidence from an old rape kit, bloody shirt, or stained bedclothes may contain a valuable DNA profile. These new analysis techniques, in combination with an evolving database system, make a powerful argument for the reevaluation of unsolved crimes for potential DNA evidence. Knowledgeable law enforcement officers are taking advantage of powerful DNA analysis techniques by investigating crime scenes with a keener eye toward biological evidence. The same new approach being applied to crime scene processing and current case investigation can be applied to older unsolved cases. Law enforcement agencies across the country are establishing cold-case squads to systematically review old cases for DNA and other new leads. This report will serve as a resource to assist law enforcement with maximizing the potential of DNA evidence in unsolved cases by covering the basics of DNA analysis and its application to forensic casework. The report will also demonstrate how DNA database systems, advancing technology, and cooperative efforts can enhance unsolved case investigative techniques.
Shortly after dawn on Tuesday, November 22, 1983 the body of a fifteen-year-old girl was found brutally raped and strangled on a narrow dirt footpath near the English village of Narborough in Leicestershire. Her name was Lynda Mann. A semen sample taken from her body was found to belong to a person with type A blood and an enzyme profile, which matched only 10% of the adult male population. Even though a massive manhunt was launched the case remained unsolved. Three years later the killer struck again, this time killing fifteen-year-old Dawn Ashforth in almost the identical spot where Lynda's body was found. Semen samples recovered from Dawn's body revealed her attacker had the same blood type as Lynda's murderer. Even though the police knew that these murders were committed by the same man, it took four years, a scientific breakthrough and blood samples from more than four thousand men before the real killer was finally brought to justice. (Lee, 1993)
Solving a murder is never easy. For the most part, unless law enforcement officials get a murderer to confess, it is often difficult to make an arrest and even harder to obtain a conviction unless there is eyewitness testimony or compelling DNA evidence. Many television shows like Law & Order and CSI have glamorized the effectiveness and efficiency of the latest advances in forensic science including the application of DNA matching to link murderers to their victims. Inevitably, within a period of an hour, these fictional detectives solve murders that could take years to solve, even with the best and brightest scientific minds working on them around the clock. On TV, the cops are always able to find DNA samples that have been uncorrupted and are rushed to the lab for processing that rivals the one-hour photo labs at Wal-Mart. The bad guys always leave something behind: a partial thumb print on a nightstand, skin under the victims fingernails, even trilobal carpet fibers that are later matched to the trunk of the murderers car.
In the real world of forensic science, things are not always so easy. In fact, DNA was not used to solve criminal cases until the 1980's. The first murderer to face justice based solely on DNA evidence found at a murder scene was Colin Pitchfork, who in 1988 was sentenced to life in prison for the murders of Lynda Mann and Dawn Ashforth.
In this research paper, I will explain what DNA is and how it is used to solve criminal cases. Additionally, I will discuss the implications of DNA fingerprinting in solving cold cases with a focus on collection methods and applications in the state of California. This research will attempt to analyze and discuss the feasibility of DNA testing in solving cold cases and will study the impact that DNA fingerprinting has had on the forensic science community as a whole. This research is driven by studies and collection methods already implemented by the scientific community as well as future methods of collecting and testing DNA evidence as it relates to the investigation of unsolved murders.
So just what is DNA and how is it being used to solved crimes that were previously unsolvable? DNA is generally used to solve crimes in one of two ways. In cases where a suspect is identified, a sample of that person's DNA can be compared to evidence from the crime scene. The results of this comparison may help establish whether the suspect committed the crime. In cases where a suspect has not yet been identified, biological evidence from the crime scene can be analyzed and compared to offender profiles in DNA databases to help identify the perpetrator. Crime scene evidence can also be linked to other crime scenes through the use of DNA databases. DNA evidence is generally linked to DNA offender profiles through DNA databases. In the late 1980's, the federal government laid the groundwork for a system of national, state, and local DNA databases for the storage and exchange of DNA profiles. This system, called the Combined DNA Index System (CODIS), maintains DNA profiles obtained under the federal, state, and local systems in a set of databases that are available to law enforcement agencies across the country for law enforcement purposes. CODIS can compare crime scene evidence to a database of DNA profiles obtained from convicted offenders. CODIS can also link DNA evidence obtained from different crime scenes, thereby identifying serial criminals. (Lee)
In order to take advantage of the investigative potential of CODIS, in the late 1980's and early 1990's, states began passing laws that required offenders convicted of certain offenses to provide DNA samples. When used to its full potential, DNA evidence may help solve and may even prevent some of the Nation's most serious violent crimes. However, the current federal and state DNA collection and analysis system needs improvements:
In many instances, public crime labs are overwhelmed by backlogs of unanalyzed DNA samples.
Labs may be ill equipped to handle the increasing influx of DNA samples and evidence. The problems of backlogs and lack of up-to-date technology result in significant delays in the administration of justice.
More research is needed to develop faster methods for analyzing DNA evidence.
Professionals working in the criminal justice system need additional training and assistance in order to ensure the optimal use of DNA evidence to solve crimes and assist victims.
According to a recent article in Corrections Today magazine, "DNA evidence is one of the most powerful crime-fighting tools since the advent of latent fingerprint technologies. It has the ability to convict the guilty and free the innocent." (Wilson, et. al. 1999) DNA is an acronym for deoxyribonucleic acid, a double-helix molecule found in the nuclei of cells. DNA is the basic building block of life and is based on the arrangement of four chemicals. The DNA of each and every living creature determines the individual characteristics that they have. "The arrangement of the three billion pairs of bases in each DNA molecule is different for everyone (except identical twins). An individual's DNA is the same in every cell, from the moment of conception to death. A person's DNA in scraped skin cells will be the same as the DNA in his blood, saliva, organs, semen or hair." (Wilson, et. al.)
The Discovery of DNA
So if DNA is the basis of life, why did it take so long for scientists to discover it? "On April 25, 1953, nine hundred words changed the world. Those words constituted…