CRIMINAL INVESTIGATION

Criminal Investigation

Criminal Investigation

Introduction

The process for criminal investigation is a broad aspect that must be critically evaluated to reach a conclusion. In this case, I have considered myself as a crime scene investigator on a homicide to recover evidence, and highlight the tools to recover evidence, packaging and safe keeping techniques, and expound the tests on evidences.

Recovery of Evidence

Recovery of Blood

For recovery of whole wet blood evidence from nonabsorbent material in a crime scene, a sterile, purple-top Vacutainer' containing EDT (ethylenediamine tetra acetic acid) preservative and blood drawing kits consisting of sterile tubing and sterile needles are recommended. The sterile Vacutainer' can be either plastic or glass. A new clean/sterile set of hemostats is required to hold the butterfly needle of the blood drawing kits. The method is simple: hold the butterfly needle with the hemostats and place the needle into the blood with the tapered edge of the needle facing down (Dressler, 2002). Next place the Vacutainer' into the holder attached to the butterfly needle via tubing. Once the operator/collector is ready, push the Vacutainer' down to puncture the septum and start the vacuum drawing the blood. After the Vacutainer' is filled with the appropriate amount of blood, it is removed. Discard the butterfly needle into the sharps hazardous waste receptacle and the remainder of the equipment into the regular hazardous waste. The Vacutainer' is the primary container. It will be placed in a plastic sterile centrifuge tube, which is used as the secondary container. The interior of the centrifuge tube will be padded with two sterile 2x2 synthetic gauze pads to act as a cushion and an absorbent material capable of absorbing the entire contents of the Vacutainer' should it be ruptured. Place the secondary container in tertiary packaging consisting of an appropriately sized nylon/polyester heat-seal bag.

Care should be used to not cover any labeling information when sealing the packaging, and all the air from the packaging should be removed before scaling. The facilitator will place the operator/collector's initials on all seals and place the package into the evidence bin for transport to the decontamination reduction zone.

Handgun and Shell Casting

Handgun and shell casting evidence can be left as three-dimensional or two-dimensional, patent or latent evidence. Regardless of the dimensional characteristics of the evidence, if it is patent it first must be documented photographically using the standard process with a tripod, scales, and oblique flash angles from multiple positions around the impression. Latent impression evidence must first be located utilizing oblique lighting techniques, ALS, chemicals, and/or powders (Amato, 2010). Once the latent impressions have been made visible they will be photographed in the same basic manner as for visible impression evidence, next, each impression must be assessed to determine if other types of forensic evidence are present. If other evidence is identified it must be documented, collected, processed, and packaged before the impression evidence can be processed and collected. The impression evidence will be assessed to determine the best methodologies for processing and collecting based upon the location, substrate, ...