Crime Scene Sketching and Processing

Crime Scenes Provide Physical Evidence This includes any objects that can establish a crime has been committed or can provide a link between a crime and its victim or a crime and its perpetrator. Crime labs run on physical evidence. First, you have to recognize that you are looking at a piece of evidence and then preserving that evidence properly.

Then, you need to classify and hopefully individualize the evidence Classifying evidence – This is when a piece of evidence can be put into a smaller group. For example, if the crime involved a gun and you can say it was a .22 caliber, you have classified the evidence….but there is more than one .22 in the world. Individualizing evidence – This is when a piece of evidence can come from one and only one source. For example, the .22 that committed the crime leaves a certain unique firing pin impression.

Sometimes the challenge is separating out the physical evidence from objects that just happen to be at the scene. Suspected arson in Beaufort, NC

Step 1 The first officer to arrive at the scene has the following responsibilities: #1 Medical assistance for individuals in need #2 Arrest the perpetrator #3 Secure the scene by excluding all unauthorized personnel from the scene

Step 2 Begin the preliminary exam Figure out the boundaries of the crime scene Figure out the perpetrator’s path of entry and exit Figure out your strategy for recording the scene with photography, sketches, and/or notes Figure out any safety concerns for you (blood, fluids, etc.)

Search Patterns The pattern will depend on the size and location of the scene as well as how many people are participating in the search.

Photography Photograph the scene in an unaltered condition. Unless there are injured parties, objects must not be moved until they have been photographed from all necessary angles. Photograph pieces of physical evidence to show their position relative to the entire scene. Take close-ups. If size is significant use a ruler or another measuring scale inserted near the object as a point of reference. If you move a piece of evidence, don’t put it back to take a picture.

Sketches Rough sketch – a draft of all essential information and measurements at the crime scene. To locate a piece of evidence, use a fixed point method. Choose two points at the scene that can’t be easily moved. Measure the distance from the object to each fixed point to locate the object in the space. Finished sketch – a neat precise rendering of the crime scene, drawn to scale

Fixed Point Method

Examples of Rough and Final Sketches

Notes Take notes throughout the processing of the crime scene including a detailed written description of the scene with the location of physical evidence recovered. The notes should identify the time, who discovered the item, how and by whom it was packaged, and where it went

Items typically collected as physical evidence and sent to the forensic lab: Victim’s clothing Fingernail scrapings Head and pubic hairs Blood Vaginal, anal, and oral swabs (in sex crimes) Recovered bullets Hand swabs (in firearm crimes)

Packaging Evidence Each different item collected at different locations must be placed in separate containers. This prevents damage through contact and prevents cross-contamination.

Typical collection kits include: Forceps Pill bottle with pressure lids are great for hair, glass, fibers, and other trace evidence Manila envelopes, screw cap glass vials are also good Do NOT use mailing envelopes (powders and other fine particles will leak out)

Two types of evidence requiring special packaging Blood stained materials should be packaged in wrapping paper, manila envelopes or paper bags. - If you put bloodstained items in airtight containers, the accumulation of moisture will encourage the growth of mold and the evidence will be destroyed. Charred debris should be stored in an airtight container to prevent evaporation of possible accelerants.

A Buccal Swab A common sample often provided is a cheek cell swab. This is a painless way to collect a DNA sample from a suspect.

Chain of Custody This is a list of all persons who came into possession of an item of evidence. The shorter the chain, the better. The chain of custody must be established whenever evidence is presented in court.

Most evidence can be shipped USPS or with a carrier like FedEx From Death’s Acre by Bill Bass. “ Six days later, a well wrapped FedEx package arrived; inside the layers of tape and bubble wrap was a box containing bone fragments – hundreds of them - burned to a crisp.” p 173 The disappearance of Sheilah Anderson

What can’t be shipped domestically? Ammunition Explosives Gasoline Air Bags

Two terms you will hear a lot: Standard/Reference Sample – Physical evidence whose origin is known such as blood or hair from a suspect. Questioned/crime scene evidence – Physical evidence whose origin is not known. The forensic scientist will compare a questioned sample to a reference sample in order to determine if they are similar.

Legal Considerations Warrantless searches are illegal (the 4th amendment) but there are four circumstances under which the police can search without a warrant….do you know what they are? Existence of emergency circumstance Need to prevent the immediate loss of evidence In connection with a lawful arrest Search made with the consent of the parties involved

Honors Extension Make sure you understand the 5th, 6th, 8th, and 14th amendments and their connection to forensic science.