In the analysis of physical evidence, the investigator needs to use scientific methods for appropriate results. Forensic scientists use those scientific methods when contacting qualitative and quantitative analysis. They use different techniques in the evaluation of evidence containing organic and inorganic matter. The information gathered while analyzing physical evidence help in court proceedings. Forensic scientist must produce enough evidence to the court in order to clear benefit of the doubt. This makes the department of forensic science to combine technology, science and art in evaluation and analysis of physical evidence. They use archaeology, dentistry and bioinformatics to analyze evidence scientifically. For sufficient evidence, the investigator uses eyewitness to prove that the evidence analyzed belonged to the perpetrator. Crime scene photographing and recording also assist in clearing the benefit of doubt in the court of law. The complexity of the society and change of criminal trends has led to the introduction of new techniques of evaluating evidence with organic and inorganic matter.
Forensic scientist need to collect enough information in quantitative and qualitative analysis. First, whether quantitative or qualitative the investigator needs to cordon the scene of the crime. This prevents people from interfering with the evidence. The investigator should not use naked hand in handling the evidence (Saferstein, 2011). He/she should use gloves to make sure that the evidence is not tampered with by the fingerprints.
Identification of unknown chemicals and carrying out qualitative analyses is complex. First, the investigator needs to identify if the unknown chemical is in solid or liquid state to reduce considerable compounds. The investigator needs also to record the color, volume, odor, density, boiling point, melting point, hardness, physical form, index of refraction and porosity. In qualitative also information about the origin of the evidence is recorded (Tom, 2008). For example, in case of blood stain, the investigator should first identify whether the blood belongs to human, dog or other animals. A match between the evidence and the suspect can be attained after narrowing the evidence to segment of population (Stuart, 2010). For example, a blood sample needs identification of blood group, examination of DNA in proteins in order to come with the conclusion of the suspect profile.
In using the quantitative analyses, the investigator should determine the amount of drug, poison or alcohol in a sample. High level of those substances may cause death. This method can also be used in pathology to determine the physical strength of the perpetrator through measuring the depth of a knife wound. In quantitative analysis the investigator also notes the blood spatter flight. The blood forms sphere shape in flight and artistic teardrop shape while standing. Determination of angle of impact also can be obtained by measuring the length of major and minor axis of the blood drop length. Other information to come up with in quantitative includes area and point of coverage, area of origin and point of impact (Tom, 2008).
Selection of analytical techniques can be achieved through categorizing substance into organic and inorganic matters. The physical evidence containing organic matter can be analyzed using different techniques. Chromatography is one of the techniques which involves separation and identification of a component of a chemical mixture. Mass spectrometry identifies organic molecules by use of fragmentation patterns. Gas chromatography and mass spectroscopy or a technique called GC/MS is effective in the analysis of gas and liquid matter. Physical evidence with inorganic substance can be analyzed using atomic absorption, x-ray fluorescence, atomic emission and neutron activation analysis (Saferstein, 2011). In determining the composition of inorganic material, atomic absorption spectrophotometry, emission spectroscopy and inductive coupled plasma techniques can be effective. The use of those techniques is difficulty though provides accurate information. It requires discipline, enough skills and knowledge for an individual to uses those techniques (Tom, 2008).
The physical evidence containing organic matter includes fibers, body fluids and pharmaceuticals among others. The physical evidence containing inorganic matters includes tools, poison, metal scrapings and explosives among others. Forensic scientist should use a combination of analytical procedures to identify physical evidence. In the analysis of some physical evidence, statistical analysis will help in making a conclusion though prove with absolute certainty may not be available (Saferstein, 2011). For example, two people can share same fingerprint and DNA profile. In this case investigator can use statistical analysis. The ballistic expert use statistics analysis in identifying a bullet in crime scene. The bullet sample found in crime scene may be similar but will never be identical. Computation analysis helps in speed and effective processing of forensic evidence (Tom, 2008). Forensic scientist needs to compile and analyze the evidence effectively before coming up with a conclusion or matching the evidence with a suspect.
In defending scientific finding and opinion conclusion in court, a forensic scientist should give complete details of the analytical process. He/she should state the dates, sample, place the sample taken and produce a photograph for more evidence. He/she should bring about facts like similarity of the sample with the suspects profile. For example, in DND analysis the investigator should state the process undertaken to examine the results which match the suspects DNA. The forensic scientist must produce enough details to clear benefit of doubt and shift the blame to the accused (Stuart, 2010).
Advancement of forensic department has helped in combating crime. Application of technological techniques in evidence analysis has also helped in determining the perpetrator. Forensic scientist should use techniques which match the technology since the perpetrators are aware of the existing techniques.