DNA as an Evidence From a Crime Scene Report

Forensic Science Information

Scientists use DNA to create an individual’s profile using samples from the individual. The sample could be bone, body tissue, hair, blood, or excretions. During criminal investigations there is need to obtain samples from the crime scene so that DNA can be extracted and compared to that of suspects or from a database (Siege & Houck, 2010).

If a sample profile created from evidence from a crime scene does not match that of a suspect, then the person was not at the crime scene or was careful enough not to leave their DNA at the crime scene. If they match then the person did contribute their DNA at the crime scene.

Although there exists the possibility of different people having the same DNA profile under a particular probe set, the chances of this happening are very small. Scientiest and crime experts agree that DNA forensic technology gives more reliable evidence than accounts given by witnesses (Saferstein, 2010).

Describe the difference between nuclear and mitochondrial DNA

The Nuclear DNA is the DNA that a person will inherit from both his parents. This is not a duplicate of either parent DNA, but is a mixture of both. Some chromosomes from the offspring may be closer to the father’s chromosomes than chromosomes of the mother and vice versa.

Mitochondrial DNA is the DNA that will be contained, as the name suggests, in the mitochondria. The mitochondrial DNA is transferred directly from the mother to the offspring and in this case, there is no DNA of the father present here. The Mitochondrial DNA does not change or get mixed up from generation to generation. It is an exact replica unlike the nuclear DNA (Turvey & Chisum, 2011).

What types of evidence might be analyzed for nuclear DNA from crime scenes

After the evidence has been collected from a crime scene for example a blood sample, it is taken to the lab where a DNA analysis is carried out. During the nuclear DNA analysis, the STR (Short Tandem Repeat) analysis is carried out to establish and distinguish DNA profiles of individuals.

The nuclear DNA analysis is helpful in solving cases that involve former convicted offenders, missing persons and cases that were unsolved and the nuclear DNA was carried out, but no match has been found to the profile. The FBI uses the STR to feed information to CODIS, a program that is used to house the database of DNA from crime scenes and suspects (Turvey & Chisum, 2011).

What types of evidence might be analyzed for Mitochondrial DNA?

Mitochondrial DNA analysis is done to examine the DNA from the evidence collected from the crime scene. Unlike the nuclear DNA analysis, the mitochondrial DNA analysis can be carried out on samples collected that do not have a nucleus such as teeth, bones, nails, and hairs.

The mitochondrial DNA (mtDNA) analysis can also be used to solve cases that go unsolved for years. When a body in a crime scene is un identified, the mtDNA of the body can be used to look for a maternal relative, therefore this method of analyzing the DNA is very helpful in solving missing persons cases (Harris,& Lee, 2000).

Definition of terms

Narcotics

These are drugs that are going to belong to the opiate family. The drugs are extracted from the seedpods of the plant (opium poppy) or can be prepared in the laboratory. Examples of these drugs include cocaine. The drug will reduce any opain experienced and will make the user feel very happy( Potter & Litman ,2010).

Hallucinogens

These drugs are going to mess the mind of the users. Users begin to see, feel, and hear things that are not real. The drugs are addictive and include LSD, certain mushrooms, and cactus juice (Kennedy & Khan, 2008).

Depressants

These substances are going to slow down the functions of the body. They mainly affect the central nervous system. These drugs include alcohol, marijuana and some prescription pills.

Stimulants

These are the drugs that are going to improve either the mental capability or physical capability or both of a person using the drug. They cause enhanced alertness as well as wakefulness. Drugs in this category include nicotine, caffeine and amphetamines (Kennedy & Khan, 2008).

References

Harris, H. A & Lee, H. C. (2000). Physical evidence in forensic science. Tucson : Lawyers & Judges Pub. Co.

Kennedy, T. J. & Khan, J. (2008). Basic Principles of Forensic Chemistry. London : Springer distributo

Potter, G. W. & Litman M. D. (2010). Drugs in Society: Causes, Concepts and Control. Cincinnati : Anderson Publishing.

Saferstein, R. (2010). Criminalistics: An Introduction to Forensic Science. Upper Saddle River, NJ : Prentice Hall.

Siege, J. A. & Houck, M. M. (2010). Fundamentals of Forensic Science. Burlington, MA : Academic Press

Turvey, B. E. & Chisum, W. J. (2011). Crime Reconstruction . Burlington, MA : Academic Press.

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