Forensic Technique Analysis

5) In the virtual museum game; 5 of the different forensic techniques used were:

Tool mark analysis- This is where the forensic investigators will photograph or sketch (when the whole area can’t go to the lab) impressions made by tools used in the crime. At the lab, they will compare tools and marked objects to identify specific tools. 3 types of tool mark impressions are: compressions; pressed into soft materials, sliding; tool scrapes across surfaces, and cutting; a combination of both compression and sliding.

Imagery/computer composite- When a witness is present; a forensic sketch artist will get as much information as possible to do a composite drawing of a suspect; either manually or use a computer. Sometimes; they will use both, using

the computer data base of facial images to help the witness better describe a clearer image. The artist will also note the height, weight, hair color, eye color, gender, race, and age of suspect. The artist is very successful by listening carefully.
Hair analysis- Hairs are picked up by using tweezers or gloved hands. At the lab; then analysed, the hair is compared to possible suspect when one is found. Analysing the hair can tell you the race, any possible drugs, poisons, or diseases in their systems. Hair contains DNA that encodes a person’s genetic make-up; which can ultimately match a suspect.
Fingerprint analysis- The most common method used is by powder being brushed on prints then lifted by using a piece of tape. At the lab digital technology is used; the automated fingerprint identification system (AFIS), now with special processes to develop prints on paper, wood, cardboard, skin, and objects that have been in water.
Wound analysis- The wounds on the body are photographed and at the lab they are further analysed by the pathologist; using class and individual characteristics. An incised wound is a cutting injury by a slicing action of a blade-type object; a puncture wound would be classed under another type of wound.
6) Gunshot Residue is from firing a weapon, which produces combustion of both the primer and powder of the cartridge. The residue of the combustion products can consist of both burned and unburned primer and powder components, and can be used to detect a fired cartridge. Gunshot residue may be found on the skin or clothing of the person who fired the gun, on an entrance wound of a victim, or on other target materials at the scene. In 1929 a German chemist named Goroncy created a test using an acetic acid solution to detect nitrate compounds. The intensity of the red color after adding the acetic acid indicated the approximate distance; however, the process gave no pattern of residue on clothes and destroyed the evidence. In 1932 Teodoro Gonzales introduced "Dermal Nitrate" in a criminal identification lab in Mexico. The test was the most popular for many years. It required the application of hot wax or paraffin on the hands of the suspect, once the substance was cool, it was removed and tested with diphenylamine; a blue color was a positive for nitrates, but has recently been unaccepted because of its "lack of specificity." Joseph Walker improved upon Goroncy's technique in 1937 replacing the acetic acid with C-acid or H-acid and using photographic paper rather than samples directly on the clothing. The use of Atomic Absorption Spectrophotometer to quantify elements in a sample started in 1955. In the 1970’s the chemical alpha-naphthylamine used in the walker test was proved dangerous and the FBI Laboratory substituted it with a chemical in one of Fritz Fiegl's spot tests in Organic Analysis known as the Griess Test. 1974 a team at the Aerospace Corporation created a scanning electron microscope with electron dispersive X-Rays that could specifically detect gunshot residue. In 2008 Garrett Lee Burleson and chemist Jorn Chi Chung Yu from Sam Houston State University created a new method of detecting various elements in gunshot residue. The Burleson test can use a tiny amount of residue and uses a new method that can even identify components in newer eco-friendly ammunitions that do not contain lead or the metals other tests used for identifying residue.
An example of a gun residue used in a case is in 2005 actor Robert Blake, was found not guilty of the shooting murder of his wife.

One of the important pieces of evidence was the absence of all but a trace of gunshot residue. It was successfully argued that the residue could have resulted from his handling of his wife's body or touching the interior of the car in which she was found. This technique is not always reliable in solving a case, for example; the Tyree Wright murder case on June 24th, 1998. Police arrested Tyrone Jones, who seemed to fit the description, and he was swabbed for gunshot residue on his hands after he was arrested. He was swabbed after being in the police car, interview room, and in handcuffs (all of which have a high probability of containing gunshot residue on its own). After analysis he was charged for murder and brought to court. Jones was sentenced to life in prison and is currently trying to get an

appeal.
7) DNA is short for deoxyribonucleic acid. It is located in the nuclei of cells, which make up the body. DNA is considered as one of the building blocks of the body.
The type of evidence you would find DNA in is almost everything from hair, blood, semen, saliva, skin, fingernails, clothing, cigarette butts, and so on. Almost anything found at a crime scene could possibly have DNA on it.
DNA is used in forensic science to analyse a wide variety of samples from crime scenes. Forensic scientists can also use DNA to find out a person’s parentage.
The process to creating a DNA fingerprint; the first step to making a genetic fingerprint requires getting a sample of DNA.

Next the restriction enzymes are used to cut the DNA into smaller pieces. Restriction enzymes work by cutting the DNA at a specific sequence and results in many fragments of different lengths. These fragments are called restriction fragments length polymorphisms (RFLP’s). These RFLPs are then put into an agarose gel. Using gel electrophoresis, the fragments are sorted according to size. When the current of the electric field is turned on, the negative RFLPs will start to move across the gel towards the positive end. The smaller fragments move farther across the gel than the larger ones. The gel is then covered by a piece of nylon and thin paper towels, which are used to absorb moisture from the gel. The DNA fragments get gently transferred from the gel to the surface of the nylon. This process is called blotting. Radioactive probes get washed over the nylon surface. These probes will join to any DNA fragments that share the same composition. The final step to making a genetic fingerprint is to place a photographic film on top of the nylon surface. The probes leave marks on the film wherever they attached to the RFLPs. Dark bands will then show up when the film is developed, which marks the length of the RFLPs. Then scientists are able to compare the DNA from the crime scene and the DNA from a

suspect.
Some of the issues with the use of DNA evidence are that of the wrongful convictions due to DNA match statistics and the use of DNA to exonerate the wrongfully convicted. Other issues that have been brought on by DNA evidence is the moral issues of storing DNA in the DNA databank and how it can tell everything about a person; even the wrongfully convicted , and may cause prejudices against a person.
Yes; I do think that someone could be convicted on DNA evidence alone, if there is a substantial amount of evidence. DNA is a person’s own make-up, it tells almost everything about us, so if there is enough evidence at a crime scene and it matches to someone, then I believe it would convict them.