Crime Scene Analysis

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CRIME SCENE ANALYSIS
Hi,
Interesting set of questions! Let's look at the questions through illustrations and examples:
What are the health and safety concerns at a murder crime scene?  How does the initial officer approach the crime scene so as not to disturb evidence?  What are the initial steps to collect and preserve evidence (see response to question one and two below; as well as examples below)?  What should officers do to secure a crime scene after assuring public safety, and the policy for contacting other agencies for chemical incidents, fires, contamination risks, and biological elements (taped off and observers with police officers surrounding the area)?  Please provide references.

Let's look a bit closer:
1. What are the health and safety concerns at a murder crime scene?  
In fact, many additional problems are caused by curious onlookers at the scene when a body is discovered. The major concern is, of course, to protect the scene from destruction or contamination by onlookers and curious police officers. The latter group usually presents the most problems. (1)

Police Officers are naturally curious and generally have to see things for themselves. Detailed follow-up investigations of many crimes have revealed that various items initially thought to be of great evidential value were actually left by curious police officers. It will never be known how much valuable time has been wasted and how much evidence has been destroyed by the mere presence of policemen. Just standing around or leaning against a doorway may grind evidence into the ground or smear a good fingerprint. Therefore, the investigator should explain these facts to the officers present and if the officers are not needed, request that they leave the scene. Most officers are cooperative and no difficulty should be encountered if the matter is presented properly. Occasionally, a problem presents itself when a high-ranking officer appears on the scene. If it becomes apparent that their presence could result in the destruction of evidence, their cooperation should be elicited in leaving the scene. (1)

How? The use of a log or name list of everyone entering the crime scene also helps discourage the curious. When good latent fingerprints are found, every person who has been present at the scene, including the victim must be fingerprinted for identification and/or elimination purposes. The police should use tact and courtesy when dealing with civilian witnesses and crowds. This approach serves several purposes. It will gain as much cooperation from people as possible under the circumstances and it may result in a witness, who is an onlooker, coming forward with valuable information. This is especially important in areas where past experiences indicates that the hostility of onlookers is easily aroused. In some situations, the mood of the crowd may become so ugly that the police are forced to leave the scene before they can complete their investigation. (1)

Also, an initial officer must notify a medical examiner to check for such things as chemical incidents, fires, contamination risks, and biological elements, and explain these facts to the observers and policeman, and any other people around the crime scene. The crime scene is often taped off to help in this protection and safety step.

Example: Notifying the Medical Examiner (excerpt)
The crime scene investigator, the detective or the supervisor on the scene should notify the medical examiner of the type of death case they are investigating. Since the determination of cause and manner of death often depends on the evidence recovered at the scene, the Medical Examiner may elect to respond to the scene personally or send one of his forensic investigators in his place.

The agency's relationship with the Medical Examiners office is crucial to the successful investigation of any case. A relationship of trust and honesty is essential. Since any investigation requires a team effort, steps must be taken to ensure that a harmonious atmosphere is in place and remains that way.
There are certain notifications that must be made during the preliminary investigation. The Medical Examiners Office should be notified and apprised of the situation as soon as possible after a murder has been discovered. They should also be notified if there is any unattended or suspicious death being investigated. If any change in status in the case occurs, they should be made aware of it. Florida law charges the Medical Examiner with determining the cause and manner of death in any case that he deems necessary, including but not limited to murder, unattended death cases, suicides and cases involving communicable diseases or public health hazards. The prompt notification will also result in the timely arrival of trained professionals who can assist the investigator in the determination of an approximate time of death (excerpted from http://www.crime-scene-investigator.net/searchingandexamining.html).

2. How does the initial officer approach the crime scene so as not to disturb evidence?  What are the initial steps to collect and preserve evidence?  What should officers do to secure a crime scene after assuring public safety, and the policy for contacting other agencies for chemical incidents, fires, contamination risks, and biological elements?  
The following example deals effectively and in some detail the initial steps in the crime scene analysis. Let's take a

closer look:
Example 1: The Initial Death Scene Examination
The crime scene examination and subsequent search should be done in a careful and methodical manner. After talking to the officer(s) who were the first ones on the scene and learning from them of any changes that might have been made to the scene since their arrival, such as turning lights on or off or opening doors or windows, start the examination by working your way into the body using great care to avoid disturbing or destroying any evidence as you do. Carefully observe the floor or ground surrounding the body. Look for items of evidence or of evidential value such as stains, marks, etc. Remember to look up too, every crime scene is 3 dimensional. Another technique to you assist in locating evidence is to shine a flashlight on the ground at an oblique angle. Yes, even in the daytime. Look at the items, as they are located. Pay close attention to everything as you approach the body at this time, do not dismiss anything until its evidentuary value can be determined. Are there any footprints or drag marks? Is there anything on the floor or ground that may be stepped on or destroyed? (1)

Only one investigator at a time should approach the body! Determine what, if anything, has been moved or altered by the suspect(s) or anyone else prior to your arrival. Has the body been moved? If so, by whom and for what reason? (1)

Never move or alter the positioning of the body! Make close visual examinations of the body and the area immediately around it. Look between the arms and legs without moving them. Look at the arms, hands and fingers. Are there defense wounds? Is there anything under the nails that you can see at this time? If you can, try to determine the cause of death and the instrument or method used. Take careful notes of the external appearance of the body and the clothing or lack of clothing. Look at or for lividity, decomposition, direction of blood flow patterns, remember the law of gravity. Is the blood flow consistent with it? Make detailed notes. (1)

Describe the clothing, and especially the condition of the clothing. Do folds or rolls indicate the body had been dragged? If so, in what direction? Note those folds and rolls, diagram them then ...