In recent times, science has provided substantial aid to crime detection.
Because anything in the physical universe has the potential of becoming an itemof evidence in an investigation, a wide variety of procedures may be used inanalyzing and interpreting evidence in a criminal case. These procedures includehandwriting analysis, forensic photography, crime scene documentation,metallurgical investigations, chain of custody, entomology, and blood spatters.The first thing you do after securing a crime scene is document it. Always takepictures. They are the best records available.
They show the crime scene as itwas found; where objects are in relation to other objects, victims, rooms, etc.Take notes. Describe the scene, its over all conditions. Describe rooms,lights, shades, locks, food; anything that can indicate a time frame, conditionof scene or that might have even the slightest evidentiary significance. Checkdates on mail and newspapers. Diagram the crime scene.
Take measurements. Photosare good to show where an object is in relation to another object, butmeasurements tell exactly how far. True handwriting analysis involvespainstaking examination of the design, shape and structure of handwriting todetermine authorship of a given handwriting sample. The basic principleunderlying handwriting analysis is that no two people write the exact same thingthe exact same way. Every person develops unique peculiarities andcharacteristics in their handwriting.
Handwriting analysis looks at letterformations, connecting strokes between the letters, upstrokes, retraces, downstrokes, spacing, baseline, curves, size, distortions, hesitations and a numberof other characteristics of handwriting. By examining these details andvariations in a questioned sample and comparing them to a sample of knownauthorship, a determination can be made as the whether or not the authorship isgenuine. Another is, Metallurgical Investigations–examinations make it possibleto identify the source of an itemwhether made of metal, plastic, ceramic, orother materialfound at a crime scene, and further, to determine if twosimilar items were fractured from each other, the nature of the force causingthe fracture, the direction from which the force came, and the time when thefragments became separated. Such identification helps trace the evidence to itsowner. The metallurgist can also restore obliterated or altered numbers onobjects of any material. Mineralogical Investigations is the science ofmineralogy is also used in crime detection. The mineralogist studies soil,plaster, cement, brick, concrete, and glass for any evidence.
Mineral analyseshave shown that differences may be detected in soil composition. Soil and dustfound on a suspect’s clothing and determined to be comparable to that at thecrime scene help to prove the person’s presence in that locality. Toxicology maybe defined as the science of poisons special methods of analytical chemistryhave been developed for use in toxicological examinations. The specimensordinarily examined in cases of suspected poisoning are tissue samples fromvital organs, blood or urine, food, drink, and the suspected poison itself.Firearms are identified through microscopic imperfections that are producedinadvertently in gun barrels during manufacture. Subsequent use and wearcontribute further to a weapon’s individuality.
Chain of Custody is of paramountimportance to any investigation. It is the unbroken sequence of events that iscaused by an item of evidence from the time it is found at the crime scene tothe time it appears in court. Every link in this chain is documented, fromdiscovery at the crime scene, through evidence gathering, storage, and labanalysis return to storage, and transfer to court. Every link is documented bydate, time, and handling individual, what was done with the evidence by thatindividual. If chain of custody is broken, if the evidence cannot be accountedin one step of its journey from crime scene to courtroom, it is renderedinadmissible; useless to the case. Blood spatters help a great deal inreconstructing a crime scene. They can be used to corroborate or disprove andalibi.
They can be used to convict the guilty. There is much more to it thanlooking at a stain or spatter and saying, “This is where the crime tookplace.” The patterns of the spatters and the shapes of the individual blooddroplets themselves can tell how the crime was committed. Drops falling fromdifferent heights (i.e.
at different speeds) will leave different lookingspatters. A drop falling from a low height of a few inches will leave a smallcohesive circle. At greater heights, the circle will be larger and may even havea ‘crown’ effect. Hitting a surface at an angle does even more to disrupt ablood droplet. Perpendicular impact leaves a droplet fairly uniform, as shownbelow. A droplet hitting a surface at an angle will bulge out in one direction,indicating the direction of travel of the droplet.
Cast off stains is a resultof blunt force trauma (beating with an object such as a hammer). Pulling backfrom a blow produces a blood spatter that indicates direction, by creating anarc of blood droplets. You can determine the number of blows inflicted bycounting the arcs. You can also determine the orientation of the individualsinvolved the size of the object used and the right or left handedness of theassailant.