Crime Scene Basics Forensic Science

Crime Scene Vocabulary CRIME SCENE: Any physical location in which a crime has occurred or is suspected of having occurred. PRIMARY CRIME SCENE: The original location of a crime or accident. SECONDARY CRIME SCENE: An alternate location where additional evidence may be found. SUSPECT: Person thought to be capable of committing a crime. ACCOMPLICE: Person associated with someone suspected of committing a crime. ALIBI: Statement of where a suspect was at the time of a crime.

Crime Scene Personnel POLICE OFFICERS are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime. The CSI UNIT documents the crime scene in detail and collects any physical evidence. The DISTRICT ATTORNEY is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge. The MEDICAL EXAMINER (if a homicide) may or may not be present to determine a preliminary cause of death. SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis. DETECTIVES interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence. They can have 30 hour days!!

Adapted from http://www.feinc.net/cs-proc.htm Crime Scene Protocol Step 1: Secure the Scene - The first step in investigating a crime scene is to isolate the crime scene so that no one can tamper with possible evidence. Step 2: Separating the Witnesses - Witnesses must not be allowed to talk to each other. This is done so they do not work togeter to create a story (collusion) Step 3: Scanning the Scene - Determine where photos need to be taken Step 4: Seeing the Scene - Take photos. Use triangulation (mathematical method of calculating the location of an object from the location of other objects. Step 5: Sketch the scene - All objects should be measured from two immovable landmarks. Label north ono your sketch. Any objects such as doors, windows, and furniture should be included. Adapted from http://www.feinc.net/cs-proc.htm

Crime Scene Protocal Step 6: Securing and Collecting Evidence All evidence needs to be properly packaged, sealed, and labeled. Also a chain of custody needs to be maintained with a chain of custody document attached to the evidence

What will evidence collected at a scene do for the investigation? Types of Evidence Testimonial evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event. Physical evidence refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession. Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells. What will evidence collected at a scene do for the investigation? May prove that a crime has been committed Establish key elements of a crime Link a suspect with a crime scene or a victim Establish the identity of a victim or suspect Corroborate verbal witness testimony Exonerate the innocent. Give detectives leads to work with in the case

Forensic Science disciplines at the Illinois State Police Crime Labs Investigating the Evidence Forensic Science disciplines at the Illinois State Police Crime Labs Drug Chemistry – Determines the presence of controlled substances and the identification of marijuana Trace Chemistry - Identification and comparison of materials from fires, explosions, paints, and glass. Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers, woods, soils, building materials, insulation and other materials. Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva. Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons. Latent Prints - Identification and comparison of fingerprints or other hidden impressions from sources like feet, shoes, ears, lips or the tread on vehicle tires. Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired bullets, cartridges, guns, and gunpowder patterns on people and objects. Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such as a hammer used to break a door or a screwdriver used to pick a lock. Questioned Documents - Examination of documents to compare handwriting, ink, paper, writing instruments, printers, and other characteristics that would help to identify its origin.

At the Crime Scene The crime scene can be any place where evidence may be located to help explain events This does not have to be the place a crime occurred If a crime scene is not treated carefully, any evidence found could be thrown out, misinterpreted, or contaminated Investigators gather information at the crime scene to reconstruct the sequence of events, to establish the modus operandi, and to find motive for the crime The modus operandi (MO) is the characteristic method of operation of a criminal Investigators must meticulously and accurately collect all evidence for scientific analysis and legal application.

The overall goal of crime scene analysis is the learn what happened and gather evidence to identify and convict criminals As a CSI, one must use their experience and knowledge to determine what objects at the crime scene are actual evidence Some items are insignificant to an investigation and would overwhelm the crime lab to test them Any errors made in protecting, gathering, and analyzing evidence cannot be corrected

Preserving and Isolating the Crime Scene The first officer on the scene of a crime has several responsibilities They should get medical attention for anyone in need. Saving lives and helping victims is first priority. Detain any suspects or witnesses Make an arrest if possible Finally, they should protect the crime scene from any unauthorized personnel who could add new material or alter evidence However, all of the previous steps may have altered the crime scene

As other officers and personnel arrive, crime scene tape, barricades, rope, and guard can be used to preserve a crime scene If a death has occurred, the medical examiner should be called to the scene Their job is to note the body's condition and if possible estimate the time of death They will also later collect any evidence found on the body and help with autopsy All personnel involved are to preserve fragile physical evidence at the crime scene Destroyed or altered evidence cannot be used

When the investigator arrives... They should conduct interviews The first responder can give an account of the initial scene and any personnel that may have contaminated it The victim and witnesses will be able to describe the crime Officers should note scene details such as: weather conditions, particular odors, are the lights on or off, any signs of prior activity, light, and visibility

Speaking of interviews … Bank robbery during live interview https://www.youtube.com/watch?v=QeJxImG2Ng4 15 minutes of fame … https://www.youtube.com/watch?v=tYtOTeIC7wk

Observing and Documenting the Scene Investigators should examine the scene to: find possible items of evidence, identify possible points of entry and exit, consider what may have happened, mentally outline how the scene should be handled They may use oblique lighting to examine surfaces for any hidden evidence that cannot be seen under normal lighting This requires investigators to use a flashlight about an inch off a surface and sweep the beam back and forth The investigator should then document everything using notes, photography, sketches and video Look at a scene ….

Notes Note taking forces investigators to be more observant Writing things down also helps an investigator remember minute details that may have been otherwise overlooked Should be taken during the entire scene processing An investigator may tape record the scene processing and this can be transcribed into notes that include the original tape

An investigators notes must be complete and thorough including: the date and time location description weather and environmental conditions crime description the steps the investigator goes through during processing with every action that occurred on the scene measurements of the crime scene locations of all evidence collected and location in reference to other evidence names of all people involved authorized personnel, witnesses, and victims any changes that occurred to the scene any other information that may be relevant Do you remember that scene?

Photographs and Videotape Photographs may capture details that even the most skilled investigator may miss Photographs should be taken before the scene is processed to ensure that they are capturing the initial crime scene these show the entry and exit, evidence in the original state, and help the judge/jury visualize the scene These should be taken from many angles including a scale for reference and closeups Videotaping is also an option as it allows an investigator to take in the whole scene and narrate their findings. This can be used as evidence as long as it is unedited. Youtube? - https://www.youtube.com/watch?v=Gr5yFxyMlS4

Sketches Along with photographs, an investigator should also make a sketch of the crime scene Drawing may help an investigator notice and remember small details These give a better layout of the scene than photographs do They also allow the investigator to be more selective and only include the evidence and other important factors leaving out other details

Some of the most important aspects of a sketch are the measurements, scale, and relative placements of all crime scene details These should also include the date and time, scale, reference points, distance measurements, names of investigators, victims, suspects, and a legend The original sketch is considered evidence and cannot be altered

Searching the Scene for Evidence Methodically and thoroughly searching the crime scene for evidence is one of the most important parts of an investigation Investigators look for anything that should not be there, anything that may contain trace evidence, and any bodily fluids these can be seen under special UV lighting Extreme care must be taken to identify, package, and label each piece of evidence Depending on the size and complexity of the crime scene, it can be searched by one person or may be split up into sections Lets revisit that scene …

Collecting and Packaging Evidence All pieces of evidence should be collected into separate containers and labeled to protect from damage or contamination The most fragile evidence should be collected and packaged first fingerprints, hairs, bloodstains, etc. If evidence is on a larger object (clothing, etc.) the whole sample must be collected and sent to the lab for processing

Some things to take into consideration when packaging evidence: Acceptable containers used collect evidence are vials, pill bottles, envelopes, plastic bags, etc. Some things to take into consideration when packaging evidence: Wet items must be dried before packaging All containers should be sealed tightly Biological items should be dried and kept in a freezer Care should be taken when packaging garments with trace evidence as to not disturb the evidence Firearms should be fixed within containers Evidence from arson should be kept airtight so accelerant fumes cannot evaporate a flammable substance used to start a fire Tape can be used to pick up evidence, but it also picks up unrelated particles A vacuum with special attachment can be used to pick up particles, but it also picks up everything

Maintaining the Chain of Custody Chain of Custody is the written record of who has possession of a piece of evidence at all times For court, there should be a complete record of where the evidence was from the time it was collected to the time it appeared in court Many times, this is a label on the evidence bag. It will show who was in contact with the evidence, what changes were made to the evidence, and what tests were run on the evidence All persons who handled evidence may be called to testify Evidence eventually ends up in the crime lab for testing

Fake evidence / crime scenes Always keep in mind that some crime scenes may be staged or contain planted evidence Arson may be used to cover up another crime A murder may be staged to look like a suicide A burglary could be staged to collect insurance money https://www.youtube.c om/watch?v=iLNtqJ_ij _A Last questions …