Scene of the Crime by Anne Wingate Read Free Book Online Page B

fixative available from supply houses is preferable. Then a portable frame—metal or wood—is placed around the track. Using the bucket and stirring stick that is part of his/her equipment, and following package directions on the bag of plaster, the officer mixes the plaster with water obtained at the scene. (Someone who habitually goes places where water is not readily available should carry several gallons of water in the trunk of his/her car.) Very carefully, pouring onto the stirring stick held just above the print in order to break the flow and diffuse the plaster mixture and keep it from damaging the print, the officer pours the plaster into the frame. The plaster is reinforced with twigs, straw, and so forth from the scene; an officer who customarily goes places where s/he cannot expect to find twigs and straw should carry Popsicle sticks, available in bulk in craft stores under the name of "craft sticks," as a substitute. It is important to avoid using twigs and straw from a different location, as that might confuse scientists who are studying the shoes and tires and the casts.
    Waiting for the plaster to dry may take anywhere from ten minutes to two hours, depending on the quality of the plaster and the atmospheric conditions. When it is nearly dry, a twig or even a finger is used as a stylus to put the officer's initials, the date and the case number in the back of the plaster. When it is completely dry, the casting is carefully lifted and put into a cardboard box upside down to finish drying. The officer should not try to clean it; that is left for the lab to do. This procedure accomplishes two things at once: it provides a cast of the shoe or tire, and it provides an exact sample of the soil, with its associated leaves, twigs and debris, in which the print was made, for comparison to the soil adhering to the shoe or tire.
    Toolmarks
    An officer should never attempt to fit a suspect tool into a toolmark; doing so would damage the evidence. If at all possible, the item the toolmark is on should be collected and packaged for transmittal to the lab. The crime-scene kit should contain a small saw, so that officers can, if necessary, saw out a section of the door frame where the pry mark is located. (I once moved into an apartment and noticed immediately that a section of an interior door frame had been sawed out and neatly painted over and several circles of carpet had been taken out and replaced with carpet almost, but not quite, matching in color. That alerted me that a major crime of some sort had occurred in that apartment.)
    If removal of the area is absolutely impossible, dental casting material can be used to obtain an exact cast of the print. The officer must follow directions on the container, as there are many different types of dental casting material.
    Fibers, Soil, Hair, Leaves, Pollen, Fireclay
    Any piece of small evidence that is big enough to see, no matter what it is, should be collected with tweezers and put into coin envelopes (if there is the slightest possibility that it is even slightly damp) or into small plastic bags.
    But what about the ones that are too small to see?
    This is when an evidence vacuum, a small, extremely powerful vacuum cleaner equipped with filters, is useful. The vacuum cleaner is first cleaned, even if it is always cleaned after use, just in case somebody else forgot to do it last time. Then the officer inserts the first filter, and choosing a small, easily definable section, such as the floorboard, passenger's side, front seat, s/he vacuums up everything in that area. Then that filter with its entire contents is placed in an evidence bag, the vacuum cleaner is cleaned again, the second filter is inserted, and the work continues.
    If the same area is going to be fingerprinted, it is essential to use the evidence vacuum before fingerprinting, to avoid contaminating the vacuum sweepings with fingerprint powder. Obviously, it takes something of a contortionist to vacuum an area