Crime scene investigation

In Mr. Kelly's class we were put into groups of 4 or 5 and our goal was to solve a crime. My teammates were: Andy Platt, Lauren Bennett, and Lena Lepari. In our crime scene we had this evidence: 2 blood sample(4D,3D), fiber, gold chain, foot print, a deodorized cotton ball, hair, and we had a potential homicide. After we tested the blood samples our results were 4D: Blood type B and 3D: Blood type: A. With this done we narrowed down our suspect to Ralf Johnson, Jenny Cho, Sam Tilson, and Mr. Popadines. On his rap sheet Sam had already been convicted of murder and jenny was wearing a gold chain in her picture. This is my crime scene scenario or what i think happened according to my evidence: One day Jenny was walking home from her work (some kind scientist) wearing her sneakers, after just having bought a refill for her favorite perfume so she was carrying it in her hand,and her favorite gold chain that had been given to her. Then Sam pops up and reels her into this alleyway, which was were the evidence was found, and he tries to take Jenny's chain but she hesitated to give it to him and so Sam out of pure anger struck Jenny which caused her to bleed(blood type A). As a defense Jenny threw her brand new bottle of perfume a Sam, which bounced off his face onto the side of the alleyway, causing his jaw to start bleeding heavily. Sam intended to do much more to Jenny but he then heard the police siren and ran off Jenni scared that she would be accused of something fled as well.
My scenario is probably not anything like my teammates and that is okay because that is the way that they viewed the crime scene.

Blood typing

In 1875 different blood types were recognized. In 1901 Karl Landsteiner named and standardized the groups. Red blood cells carry a substance called an antigen which produce antibodies to fight infections. Karl noticed this and decide to test it. He found two distinct reactions(clumping and repelling). He labeled these type A (in which antigen A was present, anti B antibody was present, but antigen B was absent), and Type B (in which antigen A was absent and antigen B was present). A third reaction was formed, C later relabeled as O, in which neither antigen A or B were present. Then another type was discovered this is known as AB, in which both antigens are present. In 1932 Dr. Leon Lattes invented a way to test for antibodies in dried blood flakes. Thanks to these discoveries doctors and forensic scientist have been able to help many people.

Hair and Fiber analysis

Two of the most important sources in forensic science are hair and fiber in most cases it is the key target to help unmask an attacker or assaulter. If a hair is found on the body or clothing of the victim it can usually determine race, sex, and to compare DNA. As for fibers they can determine what the attacker was wearing when the incident occurred. Forensics scientist use this analysis to determine the precise garment and the manufacture. Both of these samples are normally collected at the sight of the crime or at the autopsy. Police use these samples to narrow the suspect down or to eliminate some people. The samples are collected and stored in vials, tubes and grip seal bags. This is so that the samples will not cross contaminate. During the analysis the victims clothing may be searched for body fluids such as blood, semen or saliva and following this procedure scientist then look for hair not matching the victims' and any fiber that does not appear to be from the same garments that the victim was wearing. These materials are then collected and stored so that further examination can take place at later stage.

Handwriting in forensics

A persons handwriting has long been used as a form of identification. This is why people are required to sign checks, wills, deeds, and contracts. A persons handwriting and fingerprints are similar in the form that no two people wright the same way. There are two types of writing, request writing and non-request writing. Request writing is when the person sits before you and produces the writing. This type of writing usually does not carry as much weight in court because it give the person a chance to change their writing and the person will sometimes be nervous which gives inadequate results. The more familiar types of handwriting are cases in which the signed signature is questioned of being forged. A deliberately altered signature is another type of questioned signature. This is often where the person signs a document, making some noticeable changes, usually done in letter form, and then claims it is not their signature. "The cut and paste" is also another type of forgery or documetn fraud. This is usually when the person takes the original signature from the orginal document and makes a photo copy of it making it into a fraudulent document.

History of Fingerprinting

In 14th century Persia many official government documents had fingerprints, and one official, who was a doctor, noticed that no two fingerprints are identical. In 1870 Aphonse Bertillon, a french anthropologist, developed a system of identification where the dimensions of specific bony parts of the body were measured and recorded. A formula was made by reducing these measurements. According to the theory this formula would apply to only person an would not change in their adult life. This system seemed to be effective, it was difficult to search through all the measurements by hand in order to find a person with one arm that was a centimeter longer than the other. For 30 years this system was used or accepted until two men with almost the same name nearly identical measurements. After this incident the system never really recovered. In 1892 sir Frances Galton published a book establishing the individuality and permanence of fingerprints. He calculated that the chances for 2 people having the same fingerprints were 1 in 64 billion. In his book Galton identifies the characteristics by which fingerprints can be identified as. These characteristics are still used and are known as Galton details.

In 1892 an Argentinian police officer by the name of Juan Vucetich made the first fingerprinting investigation using the Galton details and the Bertillon system. In 1901 Galton's observations were revised by Sir Edward Richard Henry making it the Henry classification system. In 1903 the U.S began the systematic use of fingerprints for criminals which began in The New York State prison. Later in 1905 the US Army saw the use if fingerprints. Nearly two year later the US Navy starting using them and a year afterwards the Marine Corp followed in their footsteps. Within the next 25 years even more and more law enforcement agencies would start using fingerprints as a means of personal identification. Congress passed an act in 1924 establishing the identifications system of the F.B.I. BY 1946 the F.B.I had maintained over 100 million fingerprint cards in manually kept files. The F.B.I had planned to stop using fingerprint cards, by 1999, inside the new integrated AFIS. This would initially have 33 million computerized criminal fingerprint records. In 2005 fingerprint card record were still being processed for all identification purposes.