Use of DNA in Criminal Investigations

The use of DNA evidence in criminal investigations has grown in recent years. DNA testing has helped law enforcement identify criminals and solve difficult crimes. On the other hand, DNA evidence has helped prove that many convicted people are actually innocent.

Although DNA evidence can be very accurate, there is the danger of the evidence being compromised. Law enforcement must take great measures during the collection process to not contaminate the evidence. Since many crime scenes may have only very small samples of DNA, any contamination of the evidence could jeopardize identifying the criminal and solving the crime.

What Is DNA?

DNA, or deoxyribonucleic acid, contains all the genetic information about a person. It's the instructions for the body's entire genetic makeup. DNA is unique to each individual person. A person has the same DNA throughout his entire body, and it's located in every cell. Cells are the basic building blocks of all people.

Where Can DNA Be Found at a Crime Scene?

Since a person's DNA is located throughout his entire body, any materials left from his body at a crime scene will contain his DNA. Some examples of bodily materials that contain DNA evidence include:

Blood Saliva Perspiration Hair Teeth Mucus Fingernails Semen

DNA evidence can be found almost anywhere at a crime scene. Only a small amount of human cells are sufficient to provide DNA evidence that will help solve a crime. Much of the evidence may be found on a crime victim. Some examples of places where DNA evidence may be found include:

Cigarettes Clothes Stamps Bite marks Weapons Cups Tissues

How Is DNA Collected at a Crime Scene?

DNA evidence can be easily contaminated during collection and storage. Contamination can occur when DNA evidence mixes with the DNA of another person. Law enforcement must make sure they take all precautions to not compromise the evidence. Examples of precautions that officers should take include:

Wearing gloves Avoiding coughing or sneezing on the DNA evidence Preventing the storage of DNA evidence in direct sunlight or a warm setting Using paper bags or envelopes for storage and not plastic bags

DNA evidence usually must be stored at room temperature. Paper bags should be used because plastic bags will retain moisture that may damage the evidence.

How Is DNA Used in Criminal Investigations?

Since every person has unique DNA, the discovery of particular DNA evidence at a crime scene can help law enforcement determine who was involved in the crime. On the other hand, law enforcement can determine that a particular suspect wasn't involved by the absence of his DNA.

The technique used by law enforcement to identify people based on their DNA is called DNA profiling, or genetic fingerprinting. DNA profiling is highly accurate as long as the evidence isn't contaminated. Many of the DNA samples go into the Combined DNA Index System (CODIS), a national DNA database that's funded by the Federal Bureau of Investigation. CODIS can be used to identify possible suspects by matching DNA profiles. This database can help forensic crime laboratories at the local, state and federal levels work together to identify criminals and solve crimes.

Questions for Your Attorney

If I am arrested for a crime, do the police have the right to order me to provide a DNA sample for their criminal investigation?

If a family member commits a crime, can his DNA at the crime scene lead law enforcement to wrongly believe that I committed the crime? How similar is DNA among family members?

What procedures can I take if I believe that DNA evidence found at a crime scene was accidently contaminated by police during the collection process?

Dna Analysis Solve CrimesDNA analysis has opened new doors in solving crimes. Deoxyribonucleic acid (DNA) has been analyzed to prove innocence or guilt of suspects of crimes with great accuracy. The use of DNA analysis can be performed one of two ways to solve crimes. In specific cases where the perpetrator has been identified, DNA samples can be taken from suspects to compare with DNA evidence found on the crime scene. If the two biological evidence samples match with DNA testing, the suspect is charged with the crime.

The second way is when the suspect has not been identified by visual conformation but DNA left at the crime scene is available for analysis. Under controlled conditions, the sample of DNA evidence is analyzed and then compared to DNA databases of offender profiles. A match can identify the perpetrator of the crime. An added bonus for law enforcement is the DNA analyzed sample can be checked for any links to other unsolved crimes in the DNA databases locally, statewide and nationally.

Accuracy in testing is vital to the viability of the use of DNA to rule in or rule out suspects of crimes. In the late 1980s, groundwork was put into place by the Federal government to begin a system of national, state and local DNA databases for the storage and exchange of DNA profiles. The system was named the Combined DNA Index System (CODIS) and was made available to the law enforcement agencies for their use in solving crimes. CODIS have the ability to test and compare DNA databases profiles obtained from convicted offenders. They also have the ability to link DNA evidence from different crime scenes which can identify possible serial criminals. Because of the crime solving abilities of the CODIS, states began to pass laws in the late 1980s and early 1990s to require convicted offenders of specific crimes give DNA samples. Today, all fifty states and the Federal government have passed laws requiring this DNA sample.

DNA technology has begun to rapidly improve over the last years. The development of the "DNA chip technology" which uses nanotechnology, improves speed and resolution of DNA evidence analysis. This reduces the time needed from several hours to several minutes and is cost effective both in less capital funds needed and increase in capacity to process more cases. DNA analysis has become an irreplaceable tool in solving crimes. Like the snowflake, no two DNA samples are the same with the exception of identical twins. DNA analysis can be compared to fingerprint analysis in how matches are determined.

DNA evidence, when used to its full potential, will be able to help prevent some of the most serious violent crimes. Before this can happen the system needs to still improve:

1) Decrease the backlogs of unanalyzed DNA samples.

2) Equipment in some labs need to be updated with new technology to help decrease

delays in getting results.

3) Forensic scientists in the criminal justice system DNA crime labs must be required to have up-to-date training to be able to do their jobs at the highest level to make DNA technology work solving crimes.

First responder investigators must be trained on how to identify, collect and preserve DNA evidence at the crime scene. Officers of the courts must be educated in how DNA evidence technology and science

work. Policymakers and Lawmakers must render a basic legal structure that utilizes the technology, keeps the integrity as well as safeguard privacy to ensure the continued use of DNA testing in the criminal justice system. With all the above requirements adhered to, DNA analysis can help ensure accuracy and fairness in the criminal justice system.

Is Dna Evidence as Reliable as Forensic EvidenceForensic DNA analysis has proved to be a very powerful investigative tool used by law enforcement to solve crimes. However, compared to other forensic disciplines such as Latent Fingerprint analysis and Controlled Substances analysis, Forensic DNA analysis is a newcomer to the Forensic Sciences. Reaching slightly beyond the twenty year mark, Forensic DNA analysis has probably observed more change and scientific advances than many of the other disciplines in application today.

DNA, also known as deoxyribonucleic acid, is the primary building block of life. It provides a genetic blueprint that defines an organisms individual traits and characteristics. Forensic DNA analysis breaks open an individual's genetic code and enables the forensic scientist performing the analysis to examine certain locations (loci) of the DNA to distinguish one individual from another. It is the basic understanding of Forensic DNA analysis that:

1.) DNA is inherited from an individual's biological mother and father. Only identical siblings can have the same DNA. There are only similarities in the DNA of related individuals.

2.) DNA can be found in the nucleated cells of the body and is the same for each individual. Therefore DNA is the same in your blood, hair, bone, saliva, etc.

3.) DNA doesn't change over time. As you get older your DNA doesn't change to a different profile.

4.) DNA is relatively stable under optimal environmental conditions. Certain factors such as heat, light, and moisture can degrade DNA, however the processes used for Forensic DNA analysis are very sensitive and can detect DNA in very small quantities.

Forensic DNA analysis can be very useful in an investigation especially if the crime is of a serious and aggravated nature such as homicides and sexual assaults. Many of the crimes investigated which contain Forensic DNA evidence are generally perpetrated against individuals and therefore various DNA containing bodily fluids are left behind.

Forensic DNA analysis, although used the majority of the time to convict an offender, can also be used to exonerate an individual. Many cases in recent years have used DNA evidence to set an incarcerated individual free, due to the advances made in the science. What was once considered limited evidence prior to DNA testing is now undergoing DNA testing to determine guilt or innocence.

DNA evidence is very reliable evidence in an investigation due to the information it provides. It adds another piece to the puzzle and it is up to the investigator to utilize this information in the best way possible.

How Dna Analysis Helps to Solve CrimeEver since DNA evidence was admissible in the court of law, crime solving had gone a very long way. When DNA was allowed to be used as evidence, many convictions were overturned and thrown out of the window. Some of the common cases were assault, rape, robbery, and murder. Overall, genetic technology has revolutionized the way we can solve crimes.

DNA analysis can great a group of suspects and narrow down the group of suspects. For the most part, suspects at the scene of the crime leave all sorts of DNA in the form of blood, sweat, semen, vaginal fluid, urine, skin samples, saliva, hair samples, finger prints, and so forth. Before DNA evidence was admissible in court, many people were wrongfully imprisoned. There were also people that were wrongfully put to death.

Today, there are numerous ways that DNA analysis can be used to solve various crimes. Semen and vaginal fluid are forms of DNA that can be used as evidence in rape, sexual assault, and rape-related murders.

In regards to a rape case, there is DNA evidence in the form of blood, saliva, semen, vaginal fluid, and pubic hairs. Through this evidence, law enforcement can round up the suspects and take DNA samples. The DNA can be matched with the pubic hair, semen, blood, saliva, and other traces of DNA discovered at the scene of the rape. Not only does it narrow down the list of potential suspects, it brings authorities one step closer to the person or persons responsible for the crime.

In respect to solving sex-related crimes, DNA analysis has become incredibly useful. During sex-related crimes, there will always be traces of DNA left at the scene of the crime most of the time.

In homicides, there are traces of DNA in the form of blood, hair, skin, and urine. Unless bleach or alcohol is used in cleaning a weapon used for assault and/or murder, there will still be traces of DNA left. The DNA can be matched with the list of suspects. Also, there will be finger prints left on the weapons. Another form of DNA would be sweat. Yes, sweat can be used as a form of DNA evidence.

Overall, DNA tells a lot of things. It would be through DNA evidence that would bring the answers to the questions we seek. DNA possesses all sorts of interesting information such as blood type, gender, hormone, physical ailment, and other sorts of information. Even the smallest bit of DNA can give us many answers.

However, DNA analysis to solve crimes is not limited to animal DNA. There are instances in which plant DNA has been used. Like animal DNA, plant DNA is very different. Through plant DNA, authorities can

find out what type of tree or plant it is derived from. From there, they can pinpoint where the plants and trees are. Authorities will then learn where the crime had possibly taken place.

It would be through DNA analysis in which we find the keys to solving the various crimes. Without DNA analysis, there would still be many people wrongfully imprisoned and many cases that remain open.