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

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

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