Crime Scene Investigation

Crime Scene Investigation

Criminal Attorneys in Fort Lauderdale and the surrounding areas understand that there is an order to evidence gathering. The first evidence searched for and collected is the most fragile or the most likely to be lost, damaged, or contaminated. This is particularly true in outdoor scenes, where wind and rain may tamper with evidence. Fragile evidence might include blood, fibers, hair, even fingerprints or shoe and tire tracks.  See blog titled “Broward County criminal attorneys on Criminal Evidence Gathering”

Attorney William Ryan Moore on Fingerprint Evidence

Fort Lauderdale criminal attorneys constantly keep in mind that obvious and exposed latent fingerprints are photographed and then “lifted”- The same is true for tool marks and shoe or tire impressions, which are photographed before being lifted or cast. Fibers and hair are searched for with alternative light sources and picked up with tweezers. Carpets and furniture are vacuumed, using a fresh vacuum cleaner bag for each area. This often yields hair, fibers, and other trace material that escape the technician’s eye at the scene. In order to avoid damage and cross contamination, each piece of evidence in must be packaged separately. Most dry trace evidence can be placed in druggist’s folds, which are small, folded papers. Envelopes, canisters, plastic pill bottles, and paper or plastic bags may also be used. Documents are sealed in plastic covers for transport to the lab. Liquid evidence is put into unbreakable, airtight containers.

This is also true for solids that may contain volatile evidence, such as fire remnants that are believed to contain residues of hydrocarbon accelerants. Left unsealed, these residues may evaporate before testing can be done. Clean paint cans and tightly sealed jars work well in this situation. Moist or wet biological evidence must be placed in non-airtight containers so that it may air dry. If not, the moisture can cause mold, mildew, and bacterial growth, which can lead to decay and destruction of the sample. Bloody clothing is often hung up and allowed to thoroughly air dry. After the biological material dries, the evidence is repackaged into sealed containers.

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Defense attorneys argue that it is difficult or impossible to remove the evidence from the scene without damaging it. A tool mark on a pried window seal can be processed at the scene or the entire window frame can be removed and taken to the criminal forensics lab. Bullet holes in a concrete wall may likewise be processed on site or a portion of the wall can be carefully removed for later laboratory evaluation at the crime lab. Criminal investigative procedure dictates that another important aspect of evidence collection is obtaining proper control samples, which are samples used as a standard of comparison for checking or verifying the results of an experiment. These may come from the victim, suspect, or items at the scene. An automobile interior carpet fiber found at the scene is most valuable if control fibers are available from the car of the suspect’s vehicle. This way, the identified or control sample can be matched to the unidentified crime scene sample. Control samples of blood taken from the victim and the suspect can be matched to an unknown bloodstain found at the scene to see which one of them, if either, shed the blood.

In some criminal investigations, control samples take the form of substrates that are identical to the substrate of the evidence item in question. Criminal defense attorneys will tell you that a substrate is any object, material, or environment on which something else acts, is placed, or is combined with. For example, a charred carpet that is suspected of containing residue of an accelerant such as gasoline is best compared against the exact same carpet that is free of the suspect material. A carpet sample taken in an area undamaged by the fire may provide the known sample. If the examiner finds a suspicious hydrocarbon chemical in the charred carpet that is not present in the known sample, he can be more certain that it is indeed a foreign chemical and not a component of the carpet or its adhesive.

Defense attorneys will tell you that not all crime scene investigators are sworn police officers. Many years ago, before technology was viable resource in police investigations, crime scene investigators were always police officers. Now, many departments hire civilian specialists whose duties are to collect and examine the evidence that’s found at various crime scenes. It’s easier to separate the two positions—police officer and crime scene investigator—because of the difference in training and salaries. The job description of a crime scene investigator is wide-ranging. These highly skilled workers are trained in areas of expertise such as crime scene photography, latent and patent fingerprinting, computer technology and electronics, blood-spatter examination, firearms and ballistics, and tool and tool-mark examinations. Police detectives, especially homicide detectives, normally receive training in all the above areas.

To understand how a crime scene investigation is conducted, criminal attorneys handling the case identify the difference between a crime scene and the scene of a crime. The scene of the crime is any area where a crime has been committed. A crime scene is an area where evidence from a crime can be found. For example, let’s say a store clerk is robbed and killed during a robbery. The store where this incident took place is the scene of the crime. Hours later, the robber is driving the getaway car down a deserted country road. He rolls down the car window and tosses the murder weapon into the bushes, where it’s later found by a fanner. The area where the gun is found is now a crime scene because evidence of a crime is located there. Detectives seal the area surrounding the gun and gather any evidence that can be found. Both locations are crime scenes, but both aren’t the actual scene of the crime.

Criminal investigators handle the scene of a crime differently than crime scenes because the level of danger is often higher. Responding officers must be alert for the presence of the perpetrators and their accomplices.