Ridge counting is a technique which locates the exact points of the core and delta on a persons finger print. Forensic scientists have count all of the ridges which touch or cross an imaginary line drawn between the core and the delta. Forensic scientists should never include the core and the delta in counting, they should only count the ridges in between to get n accurate and precise match to a possible criminal. In order for a ridge to count, the width of the ridges must be equal to the width of the other ridges in the pattern.
One of the most important uses for fingerprints is to help forensic scientists link one crime scene to another involving the same person. Fingerprint identification and ridge counting can also help scientists track a criminal’s record, their previous arrests and convictions, to aid in sentencing, probation, parole and pardoning decisions. No equipment used in this analytical technique is expensive, and it is highly available and easy to transport, as someone is just needed to count the ridges that are present. The subjectivity of results here may effect the overall result, so scientists should allow more than one person to count the ridges to see if they come up with the same number. This gives a reliable set of data.
Trichology is the scientific study of the structure, function and diseases of human hair. A hair shaft is composed of three layers. The medulla is the deepest layer of the hair shaft, which is only seen in large and thick hairs. The cortex is the middle layer of the hair shaft and it provides the strength, colour and texture of a hair fibre. The cuticle is the outer layer of the hair shaft and it is thin and colourless.
Forensic scientists perform three major types of hair analysis. The first being ‘testing the hair shaft for drugs or nutritional deficiencies’ the second being ‘analysing DNA collected from the root of the hair, and the final type of analysing is viewing the hair under a microscope to determine if it is from a person or an animal.
When undergoing tests on hair, equipment needed by forensic scientists is: a microscope, microscope slide, water, hair strands, cover slip, forceps, paper and pencil for sketch. The procedure is as followed: gather a clean microscope slide and place a drop of water on it, then place several strands of the hair onto that slide that you are testing, slowly place the cover slip on top. After those steps, the examination can take place. When examining the hair the forensic scientists have to identify it. This can be identifying wether is has come from a human or an animal.
Human hairs usually have thin or an absent medulla, but animals normally have a thick medulla. The overall use of forensic trichology has played an important role in criminal justice delivery system. This serves as a massive advantage of using this analytical technique. Hair is labelled as physical evidence in many crime cases. If hair is properly collected from the scene of crime, it can then provide as a strong corroborative piece of evidence to place an individual to a crime scene.
By studying bones, a wide variety of information has become apparent from the use of professionals studying the matter. Information which can possibly be found from recovered bones includes age, gender, ethnicity, cause of death and the lifestyle that they lived. The adult human skeleton consists of 206 individual bones. When the bones come into a forensic lab, they will be cleaned and removed from any other body tissue that may be on them. When undergoing this analytical technique, it takes a lot of time and perseverance due to the bones or skeletal remains maybe being fragile depending on how old they are. Any damage done to these whilst analysing can be detrimental to results.
When analysing drugs, there are several techniques that can be used. Most focus on the molecular structures of the drug which has been found for testing. There are 5 ways of testing for drugs.
NMR works by forensic scientists taking a chemical sample and by placing a tiny amount of it into an NMR tube. The sample is then dissolved into a special solvent, then the tube is placed into the NMR. The machine is a large magnet. Some atoms that are in the sample will become excited when it is inside the magnet, and when the sample is removed, the atoms will return to their lower energy state. A computer which us connected to the machine can detect this change and will subsequently cause different peaks and bumps to appear on a diagram. The peaks and bumps on the diagram show parts of the molecular structure. An example of this is left below:
The use of NMR requires such a small sample size, so even if forensic scientists can only recover a drop of a substance they wanted to test, they can still achieve reliable results from the use of this machine. However, with that being said, this machine is extremely expensive, costing millions of pounds. This is an advantage to some, as not all facilities will have one of these available to them, so sending off a sample to a different facility may cost valuable time to a forensic case and the machines are not easily transported.
Poisons can be found in a house at a crime scene, these can range from nail varnish removers, sun tan lotions and cleaning products. Poisons create different types of symptoms and different visual identifications to the human body or surrounding items. An example of a poison is sulphuric acid. This can show signs of burns or stains on clothes, corrosion of mucus membranes of the human lips, throat and skin, internal changes in the body such as corrosion or inflammation. This is all shown in a pathology test. The use of pathology tests are usually for determining the cause and time of death by examining the tissues of the body. By knowing a victim’s medical state is important in assessing the possibility that the death occurred due to natural causes. This is an advantage as forensic scientists can be sure of how the person died, wether that be from a poison or not.
In addition to this, GSR may be present on an entrance or exit wound, or on materials that were targeted by a firearm. This could be on the persons clothes. GSR is composed of particles from the gun’s cartridge, with gun powder, tiny fragments from the cartridge case, the surface of the bullet and lubricants used on the gun. However, GSR isn’t always visible. Particles of GSR could be microscopic, not visible to the naked eye. The presence of black material on a suspects hands or clothing may not always indicate the presence of GSR, just as clean hands or clothes does not indicate the absence of GSR.
GSR is analysed by scanning Electron Microscopy. A picture is used to scan for particles of lead, barium and antimony. These are all characteristics of GSR. There is are many disadvantages when looking at Electron Microscopy. They cost a lot of money, they are big in size so they can’t easily be transported and the maintenance/repair cost is also expensive. However, the advantage is that they produce accurate and reliable results meaning scientists can figure out the GSR and link it to crimes. This type of microscope is a large, cumbersome, expensive piece of equipment, extremely sensitive to vibration and external magnetic fields.