Footwear Impressions
The correlation between footwear impressions and the ability to decipher a crime scene cannot be over emphasized. In his book, Footwear Impression Evidence, William J. Bodziak makes the comment that footwear impressions are very durable “In fact, their permanence in some cases is surprising” (1990, p. 3). Before proceeding, the difference between an impression and a print must be made clear. An impression is three dimensional having length, width, and depth, whereas a print has only length and width. Collecting footwear impressions is a complex task but with an understanding of the procedure, it can be an exciting endeavor leading to the arrest and conviction of the suspect in question.
We can think of an impression as a mold possessing the characteristics unique to the sole of an individual’s footwear. Footwear impressions at a crime scene can usually be found in sand, snow, or mud at a suspect’s point of entry or exit. And a judicious crime scene investigator will know the importance of first photographing the impression lest damage occur while procuring the evidence. The photographer should always include in the photograph a measuring scale placed close enough to the impression to detail the size of the impression. Although plaster of Paris has been used in the past, dental stone mixed with water is the most common material used to cast a footwear impression. For ease of use at a crime scene dental stone can be obtained in a pre-measured one and three-quarter pound special mixing bags or carried in a Zip lock bag.
When it is decided which impression to cast, mix the dental stone and pour the mixture into the impression holding the bag low so as not to disturb the ground, allowing the dental stone to flow out to the sides of the impression an inch or two. For impressions made on uneven ground, such as the side of a slope, construct a form around the impression being careful not to distort the impression, and then dispense the mixture into the impression, pouring from the uphill side allowing the mixture to flow evenly into and around the details of the impression. The same scenario is true for impressions made in shallow water. Fabricate a form around the impression. When the form is ready, clear away any debris floating on the surface of the water. Pour the dental stone slowly into the form allowing the dental stone to settle down through the water into the impression.
Casting footwear impressions in snow is a systematic procedure. A produce called Snow Print Wax is used to protect the snow from the exothermic reaction caused by the drying dental stone. Snow Print Wax is sold in an aerosol spray can in two colors, bright red and brown. The bright colors help highlight the details for photographing. Several layers of wax should be sprayed into the impression allowing each layer to dry a moment or so before spraying the next layer. The can should be held at a forty-five degree angle to the impression, and far enough away so the blast of the spray will not destroy any details. After the wax has dried, gently pour the premixed dental stone into the impression allowing ample time to dry.
Photographing a foot impression with a measuring scale included in the picture provided in the following link.
Tire Tracks and Snow Prints
http://www.jeffreycreid.com/impressions/Impression_tire_snow_prints/impressions_tire_and_snow_tracks.htm
The following pictures show, provided on the link below, a crime kit that can be carted to the crime scene with a hand truck. Also, there are photographs showing the dust and dirt hardening spray and snow impression wax being sprayed into footwear impressions for stabilizing the details.
http://www.leelofland.com/wordpress/?cat=9&paged=2
Fingerprinting
Police technology has advanced tremendously over the course of history. Yet there is one main type of technology that police use which dates as far back as 1350, in Persia. This technology is fingerprinting, which is used to help police identify people. In 1882 the Argentinean police decided to implement the technology of fingerprinting to solve criminal cases. The Argentineans police decision made a big impact on the police because even now, in 2009, the most commonly used technology to solve crimes for the police is fingerprinting. “The fingerprinting has become more sophisticated, and is put to many more uses.” ().
There are three distinct types of fingerprints: patent, plastic and latent. All of these types of fingerprints give police information on a missing person, or help to identify a criminal. Patent prints are “visible prints that occur when a foreign substance on the skin of a finger comes in contact with the smooth surface of another object.”(). The patents print is visible to the naked eye, as is the plastic print. The plastic prints “are visible, impressed prints that occur when a finger touches a soft, malleable surface resulting in an indentation. “(). The final prints, called latent prints are the hardest of all the three prints to discover. This is because they are invisible to the naked eye. The latent print is left on “body parts, moisture, oil and grease [and they] adhere to the ridges so that when the gingers touch an object, such as a lamp, a film of these substances may be transferred to that object.” ().
There are many ways that the police are able to discover who the print they find belongs to, two of those ways would be: during the processing of inmates to jail or prison, or getting prints from a suspect of a crime. When a person is arrested the police place their fingertips in black ink and then put them on white paper. Once the fingertip is placed on the white paper one can see the print clearly, these prints are then saved in an offender’s record. If the police find a print at a crime scene they can compare those prints with those people who have been in jail or prison in the past. The police can also get prints from a suspect of a crime and compare those prints to the ones find at a crime scene to help identify an offender.
The way the police identify the people whose prints they find is through print patterns. An English police official named Edward Richard Henry made the classification of fingerprint patterns. He classified the print patterns by four types. These patterns are called the Arch, Loop, Whorl, and Composite. There are then subgroups of all the different fingerprint patterns. The Arch pattern looks like the “ridges of the finger run continuous from one side of the finger to the other with no recurving. “ The subgroups of the arch are the Plain Arch and the tented Arch. The Plain Arch “starts on one side of the finger, and then the ridge cascades upward slightly, almost resembling a wave out on the ocean. “ The Plain Arch is the simplest fingerprint pattern. The second type of Arch, the Tented Arch “the difference in the tented arch lies in the ridges in the center, which are not continuous as in the case of the plain arch. The Ridges, which adjoin each other in the center, converge and thrust upwards, giving the impression of a pitched tent. The second pattern type is called the Loop, which looks as if the “ridges make a backward turn but do not twist. This backward turn, or loop, is differentiated by how the lop flows on the hand and not how it flows on the card on which the imprint is taken.” The two subgroups of the Loop pattern are the Radial Loop and the Ulnar Loop. The Radial Loop “ are loops that flow toward the radius bone of the hand.” The Ulnar Loop “are loops that flow toward the ulna bone of the hand.” The Third pattern type is called the Whorl. The Whorl is “patterns in which there are two or more details and there exists a recurve preceding each delta. “ There are four subgroups of the Whorls pattern. The first subgroup is called the Plain Whorl, which is when the ridges are circular or spiral in shape. This pattern is the simplest of the Whorl patterns. The second subgroup of the Whorl type is the Central Pocket. The Central Pocket “one or more of the simple recurves of the Plain Whorl recurves a second time.” The third subgroup would be the Double Loop, which is when there are two separate sets of shoulders and deltas. The fourth subgroup is the Accidental Whorl. In the Accidental Whorl the “composition of the pattern is derived from two distinct types of patterns with at least two deltas. “ The third and final fingerprint pattern is called the Composite pattern. The Composite patterns are combinations of the arch, loop, and whorl. Just as the Whorl pattern the Composite pattern has four subgroups. The first subgroup is called the Central Pocket Loop which “recurve a second time forming a pocket within the loop.” The second subgroup is called the Twinned Loop which “consist of two separate loop formations” The third subgroup of the Composite pattern is called the Lateral Pockets Loop, this patterns ridges bend down on one side before curving. The fourth and final subgroup would be the Accidental Loop which “are a combination of any two types of pattern with the exception on the plain arch the basically has no pattern.”
The police find that the Twinned Loop, and the Lateral Pockets Loop to be the hardest to locate, and classifies them as Double LoopsThe police have been implementing the technology of fingerprinting to identify criminals over two thousand years ago. It has assisted them in catching criminals, and it is one of the most commonly used technologies that the police use.
Biometrics: Iris and Retina Scanning
The criminal justice system is always changing due to new and approved discovers from updated technology. One of the longest technology’s that has been around since the 14th century is the Biometrics system. This system has been very helpful to the criminal justice system for more than hundred years. The biometrics system was first used by Joao De Barros, in which he used this process to finger print young Chinese children, from their fingers to their feet, to identify one child from another. Over the years the biometric system has been broken down into several ways of catching criminals and solving many unsolved crimes. The many elements that helps this system fight a lot of crime is broken down into different stages depending on what evidence has been brought from the crime. Depending on the crime these many elements have their own titles of which crime goes with a specific biometric feature. These several elements consist of Fingerprints and Hand Geometry, Facial and Voice Recognition, Signature and Keystroke Dynamics and lastly eye biometrics which consist of Iris and Retina Scanning. One element that many people find not realistic is the eye biometrics. Some people may think that this biometric element only exists in movies but in today’s society it is very helpful with the criminal justice system. The Iris and Retina Scanning element of the biometric system has not been used that often until the 21st century where is it starting to become one of the biggest elements in the criminal justice system.
Iris and Retina Scanning are both apart of the human eye. The Iris is located on the front of the eye while the Retina is located on the back of the eye. The Iris and Retina are very essential to the biometric system due their imperfect establishment of the human eye and it structures. When defining both of the two you have to split them into two separate categories because they have their own function which goes back to the biometric system. The iris is a small layer underneath the cornea that consists of many patterns that are close together. This small layer helps the iris scanning technology analyze and compare the many patterns of the iris and the texture that follows around the cornea into the iris patterns in the layer itself. In the 1936, an ophthalmologist by the name of Frank Burch was originally the first person to think of a strategy to use the iris patterns for identification. Many years later two more ophthalmologists by the names of Aran Safir and Leonard Flom presented the same strategy just like Frank Burch to a man name John Daugman. They asked him if it was ok for him to think a way to get algorithm for iris recognition. Daugman took the offer and presented many systems and product in 1994 that is owned by the Iridian Technologies. Since products and systems of iris scanning came about in 1994 they have been ways of trying to find a person identification of their eye. The most common method many companies and criminal teams use today is having a person have to stand at least 2 feet from the device and the let the device start working. The iris scanning will begin indicating an infrared light giving a person access or denied access to place less than five seconds later.
Retina Scanning allows a person to analyze a layer that only consists of blood vessel located in the back of the human eye. When using retina scanning the person who is conducting the study would have to be able to read patterns with great advantage, accuracy and cooperation because he or she will be elevating the person eye under a low-intensity light that has optical coupler attached to it as well. Unlike iris scanning the person who is being tested at the time cannot be wearing any glasses at the moment because it might be confusing for the device to read the person eye if they have something blocking the device way. Knowing how the retina scanning work many people have wonder when did the development of retina scanning come about. It was proposed that in1935 a man by the name of Dr. C, Simons and his partner I. Goldstein were the first people to study and observed the many characteristics of the retina and the many patterns that can be identify through microscopic technology. Almost four decades later it was proclaimed that Baton Rouge, Louisiana were first to establish a system called “Eyedentify.” Eyedentify was first used for a personal identifications unit made for commercial use but only contain retina scanning only. With today’s society the growing population of new technology being found, that even though that retina scanning is old it is still help with many privates companies. Retina scanning has been used for secure are like power plants, military bases, and secret agent hid out places. The most common place retinas scanning are being use in secure areas. People that are in these secure areas will have some type of identification with them so they can more through the facility easily. The retina scanning works a peephole of someone house or apartment. The person has to walk slowly to the device with is located on a secure door, that allows the person to align themselves with device at eye level. At this point the person has to be a least two-three inches away from the device to get an accurate result. The time for the person to get their results back will be within one-two seconds indicating if you can pass to the next door or not.
Since technology is changing due to new generation finding out many efficient ways of helping the world and the criminal justice system, it just a matter of how these people think of ideas when they have already been used doing in past history. With iris and retina scanning they have been around for a long time it was a fact that people could not think of a way that both of scanning can fit into today’s society. Looking at today’s society both of these biometric features can come in hand with the criminal justice system helping solve crimes and keeping certain people out secure areas. If it was not for the biometric system and people from past history, some of the new technology probably would have been used until thousands of years later in the thirty-first century.
