Bellringer: Answer the following in your notes Police investigating an apparent suicide collect the following items at the scene: a note purportedly written by the victim a revolver bearing very faint fingerprints traces of skin and blood from under the victims fingernails What units of the crime laboratory will examine each piece of evidence?

CSI mistakes CSI effect

Expert vs. Lay Witness

Functions of the Forensic Scientist Forensic Scientists rely primarily on scientific knowledge. However, only half the job is performed in the laboratory while the other half takes place in the courtroom. These functions fit into three categories:

1. Analyzing of Physical Evidence Physical evidence is less likely to be compromised or tainted by human emotions than eyewitness accounts from victims or witnesses the analysis of physical evidence involves adherence to: strict guidelines systematic collection organization and analysis of information OF INFORMATION (THE SCIENTIFIC METHOD) an understanding of admissibility of evidence is important Frye, Daubert, Kumho, Coppolino

2. Providing Expert Testimony Forensic Scientist are called on to evaluate evidence when the court lacks the expertise to do so Must establish competency by citing educational degrees, number of years of occupational experience membership in professional societies, special courses taken and any professional articles or books published. Cross-examination may reveal weaknesses in background and knowledge Demeanor and ability to explain scientific data clearly and logically to a judge and jury of non-scientists Must be an advocate of truth and not take a side

3. Providing Training Evidence must be properly recognized, collected and preserved if it is to have value. Many, but not all crime laboratories keep trained “evidence technicians”. Sometimes a patrol officer or detective collects the evidence. All officers engaged in fieldwork must be familiar with evidence collection. These people are trained by laboratory staff through extensive personal contact, lectures, laboratory tours and/or dissemination of manuals.

Witnesses vs. Physical Evidence Most witnesses do not intentionally lie on the witness stand Human observation is limited by memory, suggestion, and interpretation Memories can be confused or altered, but physical evidence stays the same bunny Effect video

List a situation in which a warrantless search may be justified. What is the first critical step of crime-scene investigation? Why is this step so important? List a situation in which a warrantless search may be justified. emergency circumstances prevent immediate loss or destruction of evidence search of a person and property within the immediate control of the person provided it is made incident two a lawful arrest consent by parties involved

Forensic science begins at the crime scene; It is imperative that physical evidence be recognized and properly preserved.

Securing and Isolating The first officer arriving at the scene must: preserve and protect as much as possible Priority given to those needing medical assistance and to arresting the perpetrator. Once the scene has been secured, the lead investigator determines the boundaries of the scene and establishes the perpetrators path of entry and exit.

Securing Crime scene Properly secured and protected first thorough search to be sure there are no suspects or physical danger safety PPE (personal protective equipment) Need to protect yourself: head, eyes, lungs, hands, feet, and occasionally your entire body Gloves rubber booties for your feet Goggles or a face shield Respiratory filter to protect lungs

Recording the scene Notes, sketching and photography are used. These will aid the investigation and be presented at trials. It is becoming more common to use videotape as well.

Photography should include: photograph the shoes of everyone at the scene Overview of surrounding area Points of exit and entry If indoors, each wall area should be shown If there is a body, photos should show its position, injuries and any weapons near by The surface beneath the body All items of physical evidence including close-ups A ruler may be inserted near objects whose size may be of significance. Panoramic views can be produced by pasting together images. **If any items are moved, added or have changed position photograph may not be admissible as evidence**.

Sketching Sketching is done after the photographs are taken. A rough sketch is done first Objects are located by distance measurements from two fixed points. Evidence is given letter designations A legend is included below the sketch A compass designating north is shown A finished sketch contains all of the information in the rough sketch. It is drawn with presentation in mind. Sometimes CAD is used

Rough Sketch

Finished Sketch

Notes Note taking is a constant activity throughout the processing of the crime scene Notes should include: A detailed description of the scene The location of items of physical evidence recovered The time the physical evidence was discovered, by whom, how and by whom it was packaged and marked. Other noteworthy sights, sounds, smells, etc. This record may be the only source of information for refreshing one’s memory months, perhaps years, after a crime has been processed.

Conducting a search Must be thorough and systematic Overlooked evidence can lead to accusations of a cover-up attempt How one proceeds depends on the locale and size but must include all probable points of entry and exit What to search for is determined by the type of crime, for example in a homicide the focus will be on a search for the weapon; a burglary: tool marks at the point of entry In most cases a search for latent fingerprints is required Careful vehicle searches are also done

Crime scene search patterns

Locard’s Exchange Principle The value of trace (or contact) forensic evidence was first recognized by Edmund Locard in 1910. He was the director of the very first crime laboratory in existence, located in Lyon, France. "Every Contact Leaves a Trace" The Locard’s Exchange Principle: "with contact between two items, there will be an exchange." For example, burglars will leave traces of their presence behind and will also take traces with them. They may leave hairs from their body or fibers from their clothing behind and they may take carpet fibers away with them. Source: http://www.virtualsciencefair.org/2004/fren4j0/public_html/trace_evidence.htm

Physical evidence How does the textbook define physical evidence? Physical evidence is any object that can establish that a crime has been committed or can link a crime and it's victim or a crime and it's perpetrator. Forensic science starts at the crime scene where evidence is recognized and properly preserved.

Steps in evidence collection Photography (www.mycrimekit.com) Sketches Conduct a systematic search for evidence Collect physical evidence Maintain the chain of custody Obtain standard reference samples Submit evidence to the laboratory

Chain of Custody EVERY person who has come into contact with the evidence handled examined Acts as a “paper trail” Failure to do so: lead to questions regarding the authenticity and integrity of the evidence and the examinations When evidence is is analyzed there must be a new seal made

Procedures for collecting evidence Identify the evidence (is it evidence, could it contain evidence?) Decide which type of packaging would be the most appropriate (plastic pill bottle, manila envelope, paper bag, a sealed container?) Record where evidence was found (living room, northeast corner of park, etc.) Label the evidence (victim’s shirt, hat) Date and intial (you will keep a record of when you collected the evidence and that you collected)

Tag the evidence for identification Seal the evidence (put tape on it to make sure no one else has opened/compromised the sample) Fill out an evidence submission form Maintain records on chain of custody Every person that handles the evidence needs to log it.

Types of physical evidence Paint Glass Explosives Ballistics Dust & Dirt Impression evidence Fracture matches Wounds Questioned documents Insects DNA Skeletal remains Body fluids Hairs & Fibers