Crime Scene Investigation

Crime Scene Investigation

What goes on behind that yellow tape that is always at crime scenes? What are all those guys in the funny outfits doing crawling around on the ground like that? How do those men and women figure out who is to blame for the murder? When a crime has been committed, law enforcement team members use many scientific methods, along with their natural intuition and skill, to discover who is responsible. In modern crime scenes, finger and shoeprints, hair, blood, bullets, bones, and even DNA are used to help solve the puzzle and catch the criminal.

Down though the years, there has always been a constant battle between "good and evil." Criminals find newer, cleaner, and smarter ways to kill, while the criminal investigators, forensic scientists, find newer, cleaner, and smarter ways to catch the criminal. Much of the growth in forensic science is due to the scientific discoveries of the sixteenth, seventeenth, and eighteenth centuries, including microscopes, photography, and poison detection. In 1590, Zacharias Jansen invented the compound microscope, which produced a significantly larger image than the traditional magnifying glass. By the 1880's optical microscopes and the comparison microscope had come into use. With the new and more powerful microscopes, a scientist can examine hairs and fibers, blood samples, or scraps of cloth in order to decide if they match gathered evidence (Owen 9). In 1724, a German inventor, Johann Heinrich Schultze, discovered the principle behind photographic film. About a century later Joseph Nicephore Niepce, a Frenchman, was able to produce the first "fixed" image. Later, William Fox Talbot invented the negative, which could be used to make multiple prints. By the 1870's, police were using photographs regularly to record shots of evidence at crime scenes, details of victims and their injuries, and shots of suspects after they were arrested (10). For many years criminals tried to get away with murder through poisoning their victims, often succeeding. For example, in the Shakespearian play Hamlet, the king is poisoned and the only way to prove he was murdered was to get a confession from Hamlet's uncle, Claudius. A carefully chosen poison would work slowly, secretly, and surely, without the drama and mess produced by an openly violent crime. Smart murderers who had access to certain materials could even choose a drug that would confuse investigators because it caused symptoms like heart disease, pneumonia, or other natural killers. In 1836, English chemist James Marsh developed an accurate technique for revealing traces of arsenic, a poison that was highly favored by murderers because trace amounts already exist in the human body. Marsh's test could reveal amounts as small as one-fiftieth of a milligram in a sample taken from the body of someone who had died a suspicious death. The principles of Marsh's tests are still in use today (11).

At the crime scene, the preservation of evidence is not the top priority of the police officers, ambulance crews, or firemen. Their top priority is to "preserve life and assist any victims, ensuring that they are not in any danger" (Platt 12). However, after all safety precautions are taken, the next priority is to seal off the scene and make it inaccessible to those who may contaminate or destroy crucial evidence. The more people that visit the scene, the harder it is to reconstruct what happened and to identify potential suspects. Therefore, it is important to make sure there is only one entrance and exit and that only the forensic investigators are allowed into the scene. When crime scene managers reach the site of the felony, their primary aim is to interview the police officers who first arrived at the scene in order to get any information from a witness or from what the police might have seen or done (13). After that, the first task is to search for relevant evidence as thoroughly as possible because once a scene is released, valuable clues could be destroyed, removed, or rendered worthless as evidence in court. At the scene investigators search for fingerprints, shoeprints, tire tracks, incriminating marks, and of course the infamous weapon. Once the crime scene has been thoroughly investigated and all important evidence has been clearly marked and systematically numbered, the forensic photographers are the next in the line of work to be done at the scene. The photographer's main priority is to "document" key elements of an undisturbed crime scene in relation to the surroundings, since such evidence may be moved to a forensic laboratory for further examination (14).

Forensic specialists who study guns and ammunition are known as ballistic experts or firearm examiners. Investigators' first task at the scene of a shooting is to find out how many shots were fired and to find all the bullet cartridges and any stray bullets that there may be (Platt 100). When all the cartridges and bullets are found, the next task for the investigator is to reconstruct the crime. They must find out where the shooter was and at what or at whom the shooter was firing. In the laboratory, under strong microscopes, ballistic experts can see embedded on the bullet, markings that are imprinted onto the actual bullet and the cartridge that act as its own little "fingerprint" every time the gun is fired. Examination of this "fingerprint" can lead to knowledge of the type of gun that was used and tremendously narrow the list of suspects. Once the ballistic experts have the gun's "fingerprint" they simply have to test the suspect's gun and see if the gun's print matches that of the crime scene sample. Investigators also look for gun shot residue around the bullet wound on the victim. At a close range shooting, the victim is "tattooed" by the partially burned propellant which is driven into the skin around the wound. The existence of this "tattoo" can give valuable information on how close the shooter was to the victim. Gun residue can also work in the other direction. When fired, the residue not only comes out through the barrel but also sprays out from holes around the trigger and other spaces in the gun, tattooing the hand of the shooter as well (101). If the residue sample taken from the victim matched that of the residue on the accused hand, then the shooter has been identified.

Every bone in our body can tell a story or give detailed information about a person and his life. The job of a forensic anthropologist is to listen to the bones and read the story they tell. "We're