fingerprints were first used to solve a crime in the early 20th century.
fingerprints were first used to solve a crime in the early 20th century.
when were fingerprints first used to solve a crime?
the early 20th century
since the late nineteenth century, fingerprint identification methods have been used by police agencies around the world to identify suspected criminals as well as the victims of crime. the basis of the traditional fingerprinting technique is simple. the skin on the palmar surface of the hands and feet forms ridges, so-called papillary ridges, in patterns that are unique to each individual and which do not change over time. even identical twins (who share their dna) do not have identical fingerprints. the best way to render latent fingerprints visible, so that they can be photographed, can be complex and may depend, for example, on the type of surfaces on which they have been left. it is generally necessary to use a ‘developer’, usually a powder or chemical reagent, to produce a high degree of visual contrast between the ridge patterns and the surface on which a fingerprint has been deposited.
fingerprint
fingerprints (also includes palm prints and bare footprints) are the best evidence to place an individual at the scene of a crime. collecting fingerprints at a crime scene requires very few materials, making it ideal from a cost standpoint. all non-movable items at a crime scene should be processed at the scene using gray powder, black powder, or black magnetic powder. polaroid 665 black and white film loaded in a polaroid cu-5 camera with detachable flash should be used to make one-to-one photographs of prints which do not readily lift. all small transportable items should be packaged in paper bags or envelopes and sent to the crime lab for processing. because of the "package it up and send it to the lab" mentality, some investigators skim over collecting prints at a crime scene. collecting prints at the crime scene should be every investigator's top priority. fingerprints from the suspect as well as elimination fingerprints from the victim will also be needed for comparison (the same holds true for palm and bare footprints). bite marks are found many times in sexual assaults and can be matched back to the individual who did the biting. they should be photographed using an abfo no. 2 scale with normal lighting conditions, side lighting, uv light, and alternate light sources. color slide and print film as well as black and white film should be used. the more photographs under a variety of conditions, the better. older bitemarks which are no longer visible on the skin may sometimes be visualized and photographed using uv light and alternate light sources. if the bitemark has left an impression then maybe a cast can be made of it. casts and photographs of the suspect's teeth and maybe the victim's teeth will be needed for comparison. for more information consult a forensic odontologist. much like a bullet that has individualizing striations on it, natural fingernails have individualizing striations on them. a broken fingernail found at a crime scene can be matched to the individual it came from many months after the crime has been committed. broken fingernails should be placed in a paper packet which is then placed in a paper envelope. it can then be transported to the crime lab for analysis. known samples from the suspect and maybe from the victim will be needed for comparison. handwriting samples can also be matched back to the individual that produced them. known exemplars of the suspected person's handwriting must be submitted for comparison to the unknown samples. questioned documents can also be processed for fingerprints. all items should be collected in paper containers. for more information consult a questioned documents examiner. fracture matches can positively link broken pieces at the scene with pieces found in the possession of a suspect. for example, headlight fragments found at the scene of a hit and run could be positively matched to a broken headlight (just like putting together a jigsaw puzzle) on a suspect's vehicle. larger fragments should be placed in paper bags or envelopes. smaller fragments should be placed in a paper packet and then placed in an envelope. if a root sheath is attached, then dna analysis using pcr technology can say that this hair came from a certain percentage of the population to which the suspect belongs. if there is no root sheath, then a microscopic analysis can say that the hair has the same characteristics as the suspect's hair and is similar to his or her hair. at this point, no one can say that a hair came from a particular individual. hair found at the scene should be placed in a paper packet and then placed in an envelope. if a microscopic examination is required, then 15–20 representative hairs from the suspect must be submitted to the lab for comparison. if dna analysis if going to be used, then a whole blood sample from the suspect must be submitted to the lab in a "vacutainer." contact a dna lab for more information. fibers can be said that they are the same type and color as those found in a suspect's clothes, residence, vehicle, etc. fibers should be collected in a paper packet and placed in an envelope. representative fibers should be collected from a suspect and submitted to the lab for comparison. paint can be said that it is the same type and color as paint found in the possession of a suspect. paint fragments should be collected in a paper packet and placed in an envelope. representative paint chips or samples should be collected from the suspect and submitted to the lab for comparison. glass can be said that it has the same characteristics as glass found in the possession of a suspect. smaller glass fragments should be placed in a paper packet and then in an envelope. larger pieces should be wrapped securely in paper or cardboard and then placed in a padded cardboard box to prevent further breakage. representative samples from the suspect should be submitted to the lab for comparison.
contaminated evidence