Forensic Biology in Criminal Investigations


Carl and Joseph were in the woods of Georgia in early fall. They had set up a camp because they were both deer hunters. In the fall of years when the weather is cooler, deer are very prevalent. On this cool November morning, the men were walking through the woods in their quest for deer. On the second day of being in the woods, walking through what was really thick brush and uneven terrain, one of the men slipped and fell into what appeared to be a covering of a hole in the ground. As he began to try and pull himself out, he saw several skulls and bones lying around. He immediately screamed for his friend, who assisted him in getting out of the hole. Together, they looked in and saw skeletons and what appeared to be a decomposing body.

The two men called the local police. The police arrived, secured the area, and called for the forensic team to come and investigate. You are the forensic person that has been asked to identify the 5 skeletons in the grave and the body that was only partially decomposed.

  •  Why will this particular case require the use of forensic biology? Explain in detail.
  •  When you arrive on the scene, what is your first course of action? Describe your process, and be specific.
  •  How will you avoid contamination at this stage of the investigation? Explain.
  •  How will you control the other first responders or law enforcement officers? What challenges do they pose to a forensic investigator? Explain.
  •  What will you do to identify the remains at this crime scene? Explain.
  • What is the documentation process for collecting and preserving this type of evidence? Explain.
  •  How will you transport your evidence to the lab safely? Explain.
  • Once you arrive back at the lab, what significant risks of contamination exist? Explain.
  •  How will you avoid this contamination? Explain.
  • What is the process for DNA analysis on the decomposing body?
  •  What specific tests will you use? Explain.
  • How will serology play a role in the selected testing processes? Explain.
  •  Using this decomposing body as an example, what is the process that you will follow to properly conduct this DNA test?
  •  What challenges or barriers exist when you begin to interpret the results of your DNA test? Explain in detail.
  •  How large of a role will facial reconstruction play in this investigation? Explain.
  •  Next, provide 2 scenarios of court case outcomes regarding this investigation.
  •   One scenario must result in the successful identification and conviction of the perpetrator. You will need to fill in the blanks with regard to physical evidence and other necessary details.
  • The other scenario must result in a wrongful conviction. You will need to identify the elements that lead to this wrongful conviction.

Sample paper

Forensic Biology in Criminal Investigations

Use of Forensic Biology

Forensic biology is one of the most reliable sources of crime scene evidence. The particular case will require forensic biology because it involves murder, which is a serious crime. All serious crimes attract hash punishments, which may involve spending an entire lifetime in prison (Kayser, 2017). Forensic biology will also be necessary because no human eyewitnesses are present to help solve the mysterious murders. Forensic biology will provide critical leads concerning the people who committed the murder. By examining the DNA evidence obtained from the crime scene, the law enforcement officials can be able to identify the suspects (Kayser, 2017). Identifying the suspects will require the law enforcement officials to match samples of possible suspects with those obtained from the crime scene. A non-match could be a strong indicator that the suspect was not involved.

The particular case will require forensic biology for the identification of crime victims. The case indicates that some bodies had undergone decomposition leaving skeletons while another was partially decomposed. It is not possible to prove the identity of the victims without the use of forensic biology, and in particular DNA matching. Matching DNA profiles of the crime victims with DNA profiles of people who have lost their loved ones under mysterious circumstances will help in establishing or excluding paternal relationship, and thus the identity of the victims (Kayser, 2017). It is highly possible that the crime scene contains DNA samples of the person who committed the crimes.

First Course of Action

On arriving at the scene, the first course of action will be to scan the surrounding area to ensure the safety of all officers. An initial observation of the crime scene can also help in assessing the safety of all responders. This is important for the safety of all those involved in the investigation. The second step would be to secure the crime scene. It is important to ensure that only a few persons involved in the case enter the crime scene to avoid contamination and alteration of evidence. Restricting movement of all those around the crime scene including law enforcement officers not involved in the case is critical. It will be possible to control people by using a law enforcement tape all around the crime scene. Law enforcement officers may help in preventing people from getting across the law enforcement tape. The third step is to identify important people with regard to the scene, for instance, suspects and any witnesses. Law enforcement officers should handle suspects and witnesses. In addition, they should control family members and friends.

It is important to control the first responders or law enforcement officers. The first responding law enforcement officers should control people at the scene. For instance, they may secure and separate witnesses, suspects, family members, or bystanders. The law enforcement officers should prevent all those not essential to the investigation from the crime scene. This may include politicians, bystanders, and other law enforcement officers not connected to the case. The law enforcement officers should set up a wider physical barrier considering that it would be easier to reduce it compared to expanding. First responders and law enforcement officers pose a significant challenge in that they may interfere with or alter crime evidence. For instance, first responders may move key objects relating to the crime or even take away the evidence. Another risk is contamination of crime area. First responders who stray into the scene may shed DNA materials such as hair, skin, saliva, blood, and others, thus contaminating the scene.

Identifying the Remains

The first step in identifying the remains is to look for any physical evidence present at the scene, for instance, identification cards or any other documents. If there were no documents available, it would be important to conduct a forensic anthropology. A forensic anthropology involves the examination of crime scene remains to establish critical details such as the number of people, age, sex, cause of death, events following death, time of death, and among others (Dupras et al., 2016). The first step would be to identify whether all the skeletal remains are human or nonhuman. After this, it is important to determine the possible number of the victims. A biological profile of the bones can help reveal the sex, age at death, stature, and ancestry of the victims (Dupras et al., 2016). Studying skeletal modifications can help in telling how long the bodies have been there. Facial reconstruction using computer-aided techniques would also help in victim identification. After the skeletal profiling, it would be important to conduct nuclear DNA or mitochondrial profiling to narrow on the victims’ male relatives (Dupras et al., 2016).

The documentation process would first involve ensuring that the investigator has proper gear such as disposable shoe covers, hair net, eyeglasses, facemask, and body suit. Collecting and preserving the evidence would involve a number of steps or processes. First, there would be need to take photographs of every item at the scene of crime. The photographs should have scales for proper recording of each size of the item. The investigator can place a ruler at the scene when taking photographs in order to include accurate scales (Li, 2008). The investigator can also make detailed sketches of the scene. Another documentation process is the use of videography. A log sheet would help to note the chronological order of all photos taken (Li, 2008). It would be important to document the chain of custody when evidence transfers from one person to another. Search for particular evidence, for instance, identification documents, may be conducted once photographs are taken.

The investigator must collect small items from the scene in proper materials for presentation to a crime laboratory. The investigator should document any bloodstain pattern at the scene. In addition, he/she should collect any bloodstain at the scene. The investigator should collect both dry and wet samples, for instance, dry sexual fluids where possible (Li, 2008). The investigator should use forceps to collect pieces of hair from the scene. Where nails are available, the investigator may use clean clippers to obtain samples. Scrapping the nails may also provide samples. For bones, rib bones and vertebrae would offer the most evidence. The investigator may store dry bones in a container and freeze the wet bones. Porous materials such as paper are suitable for storing dry evidence (Li, 2008). The investigator should fold clothing with bloodstains carefully not to transfer evidence. The investigator must properly mark all evidence.

Transporting Evidence to the Lab Safely

The investigator should ensure evidence is safely stored in sealed containers or plastic bags to avoid contamination. It is important to ensure fragile items such as bones do not suffer damages during transportation (Li, 2008). The storage materials should protect the skeletons from exposure to heat and humidity since this may further damage the biological evidence. To avoid inadvertent damage to the bones during transportation, there would be sorting of bones and packing according to certain characteristics. For instance, the mandible, skull, pelvis, and all long bones should go in separate boxes to avoid damages during transportation. Placing the skull and pelvis together with other bones may cause damage hence making it difficult to obtain valuable clues. For instance, the skull may crush the cheekbones since they are very fragile. Packaging of bones and teeth in boxes can help prevent damage from external objects.

Each container or bag should have appropriate labels detailing the content, data, and investigator details. All arson debris should be transported using suitable jars or cans. Preferably, the storage containers should be previously unused. The investigator should cover the cans or jars with an aluminum foil and seal with a tape. This prevents contamination and further damage from heat and humidity. All boxes should be properly packed to avoid frequent shifting during transportation. Shifting may cause extensive damage to bones. The investigator should label clothes appropriately to avoid mix up. Wet clothes should be dried naturally.  Appropriate packaging materials in this crime scene would be envelopes, boxes, and bags (Li, 2008). Plastic bags may not be appropriate especially for evidence containing bloodstains. A body bag will help to transport the decomposing body. A plastic body bag will be appropriate for this work.

Significant Risks of Contamination at the Lab

Collected evidence faces a significant risk of contamination at the lab. Contamination issues may particularly arise in polymerase chain reactions (PCR). There are three major sources of contamination for PCRs. The first source of contamination is the lab environment (Carmona, 2009). A sample may obtain contamination from a genomic DNA in the laboratory environment, for instance, genomic DNA from a worker or a visitor. Secondly, two samples may inadvertently mix at microscopic or other levels leading to contamination (Carmona, 2009). This may particularly occur when DNA samples between two or more samples transfer during the preparation stages. Lastly, contamination may occur when the current sample mixes with amplified DNA samples from a previous polymerase chain reaction (Carmona, 2009). It is possible for a laboratory technician to carry DNA from post-PCRT reactions and contaminate new reagents.

Strictly adhering to outlined laboratory procedures can help in reducing or even eliminating the risk of contamination. It is possible to avoid contamination of samples by ensuring that pre-PCR and post-PCR amplification procedures are conducted is separate rooms (Carmona, 2009). Physical separation of these spaces would reduce the chances of carrying DNA from one test environment to another. Closely linked to this, the laboratory should have lab coats dedicated for each specific area. This would ensure that a lab technician does not move contaminants on his/her clothes from one area to another in the laboratory. It is also possible to avoid contamination by using disposable work gear, such as disposable caps, sleeves, and gloves (Carmona, 2009). Work gear offers a common source of contaminants. It is also possible to avoid contamination by ensuring thorough cleaning of all workplaces and equipment before and after working on the surfaces (Carmona, 2009). The laboratory technician should expose various reagents and material to ultra violet light.

The laboratory technician should work on amplifying a single item from a particular case. It is prudent to avoid amplifying items from multiple cases since this may contribute to a mix-up (Carmona, 2009). It is possible to monitor contamination by using reagent blanks and negative control procedures. This consists of samples having the different reagents used in the process, with the exemption of the template DNA. The PCR negative samples helps in detecting foreign DNA in the test environment (Carmona, 2009). The laboratory technician conducts the PCR negative tests using the same procedures and in the same environment with the PCR positive tests.

Process for DNA analysis on Decomposing Body

One may use a number of tests. If there are hardly bloodstains on the crime scene, it is important to conduct presumptive testing for blood (Mozayani & Noziglia, 2011). This may help in identifying materials that has blood irrespective of whether the blood is invisible to the naked eye. Another possible test is species testing blood. This involves antigen-antibody reaction using blood strain extracts. Species testing of blood may help determine whether all the blood strains are of human origin. Acid phosphate screening may help evaluate the possibility of seminal fluids on the body or cloths (Mozayani & Noziglia, 2011). Acid phosphate screening is inadequate as a lone test to confirm the presence of seminal fluids. The use of Brentamine test can help narrow down on non-stained areas that could be having seminal fluids. Items likely to contain spermatozoa may be further analyzed using a microscope. This may help to confirm the presence of spermatozoa.

Serology will play a critical role in the selected testing processes. Serology entails the identification and testing of different body fluids such as blood, saliva, urine, and seminal fluid. Serology analysis can help in identifying bodily fluids at the crime scene (Mozayani & Noziglia, 2011). For instance, serology may confirm the presence of seminal fluids in the crime scene and thus influence the testing process. Serology enables the forensic scientist to conduct presumptive and confirmatory tests on items. Presumptive tests helps in narrowing down on particular items in the crime scene. Presumptive tests confer the information that certain body fluids might be at the crime scene. The forensic scientist conducts more tests to confirm the presence of the body fluids.

One may use various processes to conduct DNA analysis on the decomposing body. A decomposing body would still have vast amount of DNA left. One of the possible tests is PCR-based STR. The DNA contains segments that have repetitive sequences. The sequences of repeats across individuals are significantly variable. Repeated segments are known as short tandem repeats (STRs) (Mozayani & Noziglia, 2011). The STRs can be critical in identification purposes. STR techniques are better compared with traditional techniques because they allow the researcher to use a small amount of DNA sample to obtain results. The STR technique is also quicker and accurate in evaluating of human DNA. STR technique can allow the researcher to establish the complete DNA profile for remains that had undergone severe decomposition or had exposure to extreme conditions.

There are certain challenges or barriers that come into play when interpreting the results of the DNA test. The first challenge relates to the matching of profiles for individuals, or in this case the skeletons and the evidence used (Mozayani & Noziglia, 2011). It is not possible to confirm a match since there exists the possibility that if other locations on the particular DNA are tested, they may yield different results indicating a non-match between the sample/evidence and the victim’s DNA profile. The accuracy of the STR analysis would therefore depend on how rare the alleles are and the number of loci examined (Mozayani & Noziglia, 2011). Another challenge is that the decomposing body may have two or more alleles on the same or different loci. Presence of two or more alleles could be an indicator that there was mixing of DNA. For the researcher to confirm the alleles, he/she must collect bodily fluid from the decomposing body’s actual fluids. Another challenge may arise when the DNA has varying intensity levels, meaning that the forensic scientist fails to identify all alleles. In such a case, it may not be possible to confirm whether a particular individual was present.

Role of Facial Reconstruction

Facial reconstruction will play a critical role in this investigation. Facial reconstruction can help in identification of victims when other methods fail to yield expected results. The use of modern software technology can allow forensic scientists to reproduce the facial features of an individual with a higher degree of certainty. With the reproduction of facial features, it becomes possible for friends or close family members to identify the victim. According to Gupta et al. (2015), the current improvements in 3D technology have led to a higher degree of accuracy in facial reproduction. The Manchester method has been particularly effective in the identification of individuals. Besides identification by family members and friends, facial reconstruction allows the forensic scientist to develop a list of possible victims (Gupta et al., 2015). The forensic scientist can them use multiple procedures to narrow down to a particular individual. As such, facial reconstruction will be critical in solving this case because most of the victims’ remains are only skeletal tissues.

Two Scenarios of Court Case Outcomes Regarding the Investigation

One of the possible scenarios is the successful identification of the perpetrator. This might be possible if the evidence available yields valuable clues leading to the arrest of the perpetrator. After combing through the crime scene, the forensic scientist discovered some pieces of undergarments believed to be from the decomposing body. A visual test using ultraviolet light was conducted to establish the presence of acid phosphatase. The test results were positive. Positive swabs of the clothing were then smeared on a slide and stained using red and green stain for visualization. Spermatozoa heads appeared red in color with blue-green tail. This confirmed the presence of spermatozoa on the decomposing body. DNA was extracted from the clothing and quantified using Short Tandem Repeat (STR) analysis. The DNA profile matched that of Craig David, a ‘jail bird’ who has been arrested on different occasions for various felonies such as drunk driving. Craig David is also suspected of a string of robberies in the area.

Another scenario in this case is a wrongful conviction. Craig David’s DNA matched 10 out of 13 alleles occurring in the DNA mixture not belonging to any of the victims. David named another suspect, Michael, whom he is believed to have a long time grudge as his accomplice in the murders. A DNA test revealed that Michael had two of the alleles being similar to those of the DNA mixture found at the scene of crime. The investigators concluded that Michael must have been an accomplice, although he vehemently denies this.


Carmona, R. (2009). Biology, conservation and sustainable development of sturgeons.      Dordrecht: Springer.

Dupras, T. L., Schultz, J. J., Wheeler, S. M., & Williams, L. J. (2016). Forensic recovery of         human remains: archaeological approaches, second edition. Boca Raton, Florida: CRC   Press.

Gupta, S., Gupta, V., Vij, H., Vij, R., & Tyagi, N. (2015). Forensic Facial Reconstruction: The    Final Frontier. Journal of Clinical and Diagnostic Research : JCDR9(9), ZE26–ZE28.   

Kayser, M. (2017). Forensic use of Y-chromosome DNA: a general overview. Human      Genetics136(5), 621–635.

Li. R. (2008). Forensic biology: identification and DNA analysis of biological evidence. Boca      Raton, Florida: CRC Press.

Mozayani, A., & Noziglia, C. (2011). The Forensic Laboratory Handbook Procedures and          Practice [recurso electrónico]. Estados Unidos: Humana Press.



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