Opportunity Create Evaluate Impression Evidence. As Read

¶ … opportunity create evaluate impression evidence. As read textbook, pattern evidence, part, examined naked eye. Select learning activities base assignment. a. Create impression patterns choice.

Impressions: Footprints and tire marks

The first of the forensic impressions I selected for my analysis consisted of footprints. "Impressions occur when two objects come in contact with one another, and one object leaves behind distinguishing markings on or in the other" (Gaensslen & Larsen 2013: 213). A footprint is classified as an impression because it has depth (three-dimensional character) in material space (Gaensslen & Larsen 2013: 213). "A positive impression is identical to the object that made it, whereas a negative impression is its mirror image. The shoe prints left in the mud are negative impressions; they are negatives of the shoes' soles. In this scenario, the positives would be the shoes' soles" (Gaensslen & Larsen 2013: 214). In this instance, the impression of the shoe is photographed as a method of preserving the impression: there is a measuring stick next to the shoe to discern its type and size (and the likely gender of the wearer).

Although the evidence of a shoe's imprint is not conclusive evidence, if the suspect has a comparable foot size and owns shoes similar to the footprints presented as evidence, this could be used as part of the circumstantial evidence against him in a court of law. In the absence of a suspect, a footprint could suggest the perpetrator was of a particular gender or occupation, based upon the construction of the shoe and also the gait. The location of the footprint in the sand could also suggest how the crime was committed -- for example, if the footprints of the perpetrator were moving away in a particular direction. "If footprints are deep and the pace is long, rapid movement is apparent. Long strides and deep prints with toe prints deeper than heel prints indicate running; Prints that are deep, short, and widely spaced, with signs of scuffing or shuffling indicate the person is carrying a heavy load" (Murray n.d.).

Footprints, it should be noted, are not as conclusive as fingerprints or DNA but if the walk or gait of the person who left the footprints; sole or heel indents; cuts or the tread of a shoe; and other signs of wear associated with a shoe" are consistent with the scenario presented by the prosecutor in court, they may encourage a jury to convict the defendant (What is a footprint, 2013, Legal Match). An expert witness in impressions will likely be called to establish the connection between the defendant and the footprints beyond a reasonable doubt.

After the photograph is taken of the evidence, a cast is taken of the footprint, usually using dental stone. "This is a special finely ground plaster used by dentists to make molds for restorations. It is mixed with water to make a pancake-batter consistency mixture, then poured into the indentation so as not to disturb any of the detail present. Once it hardens, it can be removed. It captures fine detail quite well" (Gaensslen & Larsen 2013: 215). If the model and size is determined, the forensic lab may find a 'real' copy of the shoe for even more exact comparison with an 'inked' version of the replica.