Biological Evidence Obtained at the Crime Scene


Write a 1,100-word paper that examines biological evidence obtained at the crime scene. Address the following in your paper:

Describe the biological evidence obtained at the crime scene.
Identify the preservation and collection of the various types of biological evidence.


Biological Evidence Obtained at the Crime Scene


Introduction. 2

Biological Evidence. 2

Collecting and Preserving Biological Evidence. 3

Conclusion. 5

References. 6


A crime scene refers to that place a crime has taken place and where evidence may be found and examined. Biological evidence encompasses the samples of biological material found at crime scenes that may include hair, sperms, teeth, tissues, saliva, or blood. Crime scenes have physical evidence that refers to things left at the scene that can be used as evidence in a court including fingerprints. For successful case proceedings, there is a need to sample as much evidence as possible because eyewitnesses can be lacking, and not all eye witness accounts can be truthful. This essay examines the biological evidence that may be found at a crime scene as well as the collection and preservation of biological evidence.


Biological Evidence

As stated earlier, biological evidence refers to biological material that can help trace an offender due to DNA (deoxyribonucleic acid) left behind from contact. DNA isa nucleic acid found in cell nucleus which facilitates the transmission of one’s genetic information (Naughton& Tan, 2011). Some of the bodily components that can be used to obtain DNA include hair, blood, sweat, saliva, bones, and teeth. Blood evidence is the most crucial type of evidence from scenes as it can be used to establish a strong link between an individual and a crime. When collected and stored accordingly, it can be brought up in courts to either back up or contradict witness accounts (Wheate, 2010). Blood samples direct investigators on the direction to take to solve the case. Technological progress in DNA screening since the 1990s has made biological evidence efficient.

Evidence from sexual assault scenes could be from bodily fluids and biological material left in clothing and beddings. Items such as masks, gloves, jewelry, and hats could be left behind and will most likely contain substantial amount of DNA. Beddings like sheets, pillows and pillow cases, and blankets also provide crucial biological evidence. To confirm if suspects are guilty after they have been apprehended, cheek swabs can be taken or fluids such as semen and saliva can be used. Worth to note is that DNA evidence has to be coupled with other factors to enhance its effectiveness in investigations (Menaker, Campbell & Wells, 2016).

Hair can be found in the same items as the ones named above. Fingerprints can be found on handled tools and weapons and since every individual has a unique print, it provides initial clues to possible suspects. Cigarette butts as well as things that have been licked such as envelopes and drinking containers may have saliva. All these types of biological evidence can be present in a crime scene and the named items can be used for investigation. Importantly, investigators should test and analyze all evidence collected to be able to achieve conclusive results and judgments.

Collecting and Preserving Biological Evidence

Recklessness in collecting, handling, preserving and retrieving biological evidence can contaminate and alter the integrity of the sources. Therefore, due to the sensitivity of biological evidence, there isa need to be careful and cautious when handling crime scenes. In order not to tamper with the site, lines are drawn to keep away unauthorized persons. In addition, collection materials and tools should be free from DNA to ensure they do not mix with the biological evidence being collected which could result to the conviction of the wrong person (Naughton& Tan, 2011). Safety measures such as the use of disposable latex gloves, avoiding smoking, eating or drinking are encouraged to promote the integrity of the evidence. Besides, reckless use of detection techniques like luminal could interfere with integrity of a crime scene.


Meanwhile, the recreation of a crime scene is important as it helps investigators focus on what could be used as evidence and possible happenings in the scene (Baber & Butler, 2012).During investigation, the evidence must be identified to determine how it will be collected. Clear plastic bags that are sealable can be used to store the items found that could contain evidence. As mentioned earlier, they include clothing, toilet supplies (like tissues, cotton wools and towels), cigarette butts, beddings, licked surfaces like envelopes among other things. Collection could involve picking, swabs, photographs and analyzing bodily harm like bites and scratches. Important details like whether the evidence was found wet or dry should be included in reports when collecting data.When evidence has been collected and is being transported to police stations or laboratories, it is important to keep it from conditions that can degrade the DNA like heat or cold.

Preservation is also crucial, though it may depend on the urgency of the evidence, meaning storage can be for short-term or long-term periods. Short-term preservation is ideally for materials that are being constantly required during investigation and litigation. On the other hand, long-term preservation suitable for evidence from cold cases, inactive cases or for use after litigation. The size of evidence can also determine how it will be preserved.For instance, it would be expensive to hold a vehicle for a long period of time, hence, photographs will be more reasonable or the evidence part taken and preserved instead of holding vehicles that will take up much room.

Biological evidence that is dried up could be preserved in facilities that do not have excessive heat or moisture which includes prevention from direct sunlight. This degrades DNA which could interfere with results when analysis is done. Alternatively, if it does not produce a bad smell, it could be stored in a plastic bag that can be sealed. Freezing can be used as an option for items and fluids that cannot be dried. Bones, hair samples and teeth can be stored wet to prolong their durability. Materials used as evidence in the same case can be put together to ease reference and minimize space usage. All these should be from contamination of evidence and should be locked up or sealed.

Proper documentation is important to avoid contamination of evidence as well as improve its integrity. Thus saying, fewer people should be allowed to handle the evidence and those that have access to them should be identified. Loss of evidence could slow down an investigation processor result to restarting afresh which would be expensive to those involved and delayed justice to victims.


As explained in this paper, a crime scene should be protected from contamination in order to get correct samples of biological evidence which ultimately will lead to success in investigation. Biological evidence has made a great leap in investigation and litigation processes since it is almost hard to discredit accurately examined and analyzed results from DNA analysis and the results play a significant role in case building (Wheate, 2010). The uniqueness of DNA makes it possible to trace the involved persons by examining biological material they could have left behind including blood or blood stains, saliva, sweat, hair, and teeth. That said, it is clear that it should be handled cautiously all along, from when it is collected and transported to when it is being stored and retrieved to avoid contamination.


Baber, C. & Butler, M., (2012). Expertise in Crime Scene Examination: Comparing Search Strategies of Expert and Novice Crime Scene Examiners in Simulated Crime Scenes. Human Factors, 54(3), 413-424.

Menaker, T.A, Campbell, B.A. & Wells, W., (2016). The Use of Forensic Evidence in Sexual Assault Investigations: Perceptions of Sex Crimes Investigators. Violence Against Women, 23(4), 399-425.

Naughton, M. & Tan, G. (2011).The Need for Caution in the Use of DNA Evidence to Avoid Convicting the Innocent. The International Journal of Evidence &Proof, 15(3), 245-257.

Wheate, R., (2010). The Importance of DNA evidence to Juries in Criminal Trials. The International Journal of Evidence & Proof, 14(2), 129-145.

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