Policies and Procedures Forensic Science



Forensic science aims at finding a connection between the clues and evidence that are found on the crime scene to make it credible using systematic approach. The practitioners utilize whatever tools that are available inclusive of advanced technology to collect and analyze the broken pieces of evidence obtained at the crime scene (NRC-US, 2009 p 128). Even though most of the procedures used in forensic study are based on scientific research and development such as DNA analysis, forensic pathology, toxicology etc, some are based on experience of the practitioner, reasoning and on observation (NCC-US, 2009 p 128). The pieces of evidence could be biological such as saliva, blood, semen or even animal’s fur that could be found at the scene or on a weapon considered to have been used to commit a crime. Usually analysis of the biological evidence is more difficult as most may not be visible through the naked eye and have to be collected using the aid of technological devices and are also sensitive to handle since a simple error could lead to the wrong conclusions. DNA analyses though reliable and have been accepted world wide may encounter the mismatch of labeling at the laboratory which may cause deviation.

Policies and procedures

It is known that for a piece of evidence to be credible it must adhere to the systematic approaches set by the forensic discipline. It is required that the evidence presented must state the scientific methodology applied and it becomes reliable only to the extent it has used the conventional forensic science. The practitioners are expected to integrate the use of procedures that remove bias and error as well as the relevance of subjectivity (NCC-US, 2009 p 111).

Scientific approach assumes that actions in an event follow a particular procedure which is consistent with similar cases of events for example in the case of rape there could be screaming, followed by struggle to get free from the culprit, blood, semen, saliva could also be left on the victim’s body. Since some rape are committed by persons who were presumably friends these procedures may slightly change which bring out the need for comparison from other similar cases. There are a series of steps that result in the accumulation of data that lead to the same conclusion. The weaknesses and strengths of the evidence are evaluated (NCC-US, 2009 p 112).

The investigator is required to avoid bias as much as possible and use the practices in place to detect biases such as the ones derived from interpretation and measurement as well as reduce their effect on the outcome of the investigation (NCC-US, 2009 p 112). Where necessary the investigator may use scientific principles such as the laws of natural sciences to support their explanations. With these the interpretation will least rely on the subjectivity of the investigator but on scientific principle and the general understanding of the forensic team. It is also necessary that there be a process of testing the theories under different conditions so as to ascertain the cause of the findings to be a particular variable.

Good practices also site the importance of sharing ideas and findings so as to bring on board questions and verifications. The best platforms for the presentations are in conferences, publications and colleges which may result in incremental knowledge and new findings. There is the need to have a clear record keeping arrangement and integrity among such groups who work for the same results of investigation to avoid where a team aligns itself with an investigation done by others which would result in conflict of interest (NCC-US, 2009 p 112) or where criticism is as a result of selfish interests. Still the presented evidence is acceptable so long as it is systematic and follows the structure of laid down theories.

In application of new methods that have not undergone sufficient study it is required that the method be indiscriminate about what other familiar methods’ hypotheses also to give an assessment on the sources of error and biases that could be incurred as a result of using the method (NCC-US, 2009 p 113). For laboratory testing there is a requirement to include the calibration in standard referencing, comparisons of the outcome got from other methods and other laboratories, systematic of factors that have an impact on the result and a clear statement of the presence or absence of uncertainty using theoretical principles (NCC-US, 2009 p 114).

Importance of written documentation

The CSI (the crime scene investigator) arrives at the scene at the first opportunity and conducts an observation to identify valuable and broken pieces of evidence. To ensure that the integrity of the evidence is not questionable they take photographs of the scene before beginning their collection and scrutiny of the surfaces (Pyrek, 2007 p 43). The photos provide a permanent historical source at whatever time it is required for presentation.The importance of documentation is to avoid instances of tampering, planting and contamination as well as from accusations of engaging in such interference of evidence. Written documentation is also established to support and create relationships with the photographic data. They are also used to record the observation of the investigator on the scene as well as telling the where a piece of evidence was spotted on the scene in case it is collected or changes location (Pyrek, 2007 p 43). Biological evidence such as blood samples have to be photographed before they are collected as well as well as fragile evidence that can easily be lost, contaminated or altered.

The documentation also bears useful information such as when the evidence was collected, the name of the persons involved in collecting the evidence, description of the items collected as evidence and their specific identification codes and their location at the scene which may include sketches, notes and measurements (Pyrek, 2007 p 44). The main for documentation is identified as to provide a permanent verification of what is held in custody as evidence (St. Clair et al, 2002, p 289).

Functions of crime laboratory instruments

The function of instruments in the laboratory can be divided broadly into two: to separate poisons and drugs from tissue or blood and then carry out the process of identifying the drugs and poisons; this is specific to toxicology (Mozayani, 2011 p 389). In the identification process detectors such as the flame ionization detector (FID), the UV detector and others are used to give specific distinction and also to compare results (Mozayani, 2011 p 390).

The laboratory also carries out latent finger print examinations, examination on documents to verify if they are authentic and on other items collected as evidence, trace evidence examination on biological fluids, forensic biology and molecular biochemistry such as the ones conducted for DNA analysis (Pyrek, 2007 p 41).



The importance of laboratory certification and equipment calibration

Certification ensures high level of accountability when it comes to fiscal and operational efficiency. It also ensure that the organizations operate under the appropriate laws and work towards giving a results that are accurate, sufficient, fair and objective to the benefit of justice for everyone in the society (Pyrek, 2007 p 42).

Calibration is the process of confirming that particular equipment performs the functions stated by the manufacturer. The equipment is set in the correct set-up then tested under varying and known conditions to verify their accuracy. Calibration is essential in quality assurance and that the performance of the equipment may or may not vary with time or place or where the results can be adjusted to give out the results intended by the investigator (Mozayani, 2011 p 353).


The forensic research depends on the aid of technological advancement to keep up with the level of crime and the improving skills of those that are committing crime such they are leaving lesser and lesser broken pieces of evidence. The credibility of the evidence presented and the correlated results are only acceptable so long as they are supported by theoretical and systematic analysis. Equipment calibration is necessary to ensure quality and that the outcome cannot be influenced by adjusting somewhere on the equipment. Documentation is necessary to have a listing of permanent evidence and the source.









Mozayani, A. (2011). The forensic Laboratory Handbook procedures and practice.

New York: Humana Press, Springer Science+Business Media

National Research Council Committee-US. (2009) Strengthening forensic science in the

United States: a path forward. Washington, DC 200001: The National Academies


Pyrek, K. (2007)Forensic science under siege: the challenges of forensic laboratories and

The Medico-Legal investigation system. California, San Diego: Elsiever Academic Press.

St. Clair, J., St. Clair, M W., Given A J. (2002). Crime laboratory management.

San Diego, California: Elsevier Academic Press.


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