Chapters 1 & 2 Hi Guys! How many of you are actually writing this down without thinking about it? 1 Crime Scene Investigation

Forensic Science: Fundamentals & Investigations, Chapter 2 2 Principle of Exchange Dr. Edmond Locard, director of the world’s first forensic lab (1910, Lyon, France), established the idea of the exchange principle; namely that: 1. When a person comes in contact with an object or another person, a cross-transfer of physical material can occur. 2. Study of the material can determine the nature and duration of the transfer.

Forensic Science: Fundamentals & Investigations, Chapter 2 3 Types of Evidence Statements of a witness in court would be direct evidence. Indirect or circumstantial evidence, such as a fingerprint (physical evidence) or blood or hairs (biological evidence), would imply something, and is called trace evidence.

Forensic Science: Fundamentals & Investigations, Chapter 2 4 The Six S’s of Crime Scene Investigation 1. Secure the scene. 2. Separate the witnesses. 3. See to it that the crime scene examiners receive overall and close up photos with and without measuring rulers. 4. Sketch the scene. 5. Search for evidence. 6. Secure the collected evidence.

Secure the scene 1. Establish a perimeter. 2. Limit access to scene. Police and possibly a district attorney. Crime scene investigators. Medical examiners. Detectives. Specialists. 3. Maintain a log of who enters/leaves scene. Forensic Science: Fundamentals & Investigations, Chapter 2 5

Separate witnesses Interview separately Accuracy of accounts – Can’t influence one another – Can’t alter stories to align Forensic Science: Fundamentals & Investigations, Chapter 2 6

Photograph the scene 1. Overall photos of scene  First, try to get the entire scene in the photo  Next, move closer, photographing areas of interest (clusters of evidence) 2. Close ups of evidence  Photograph each piece of evidence with & without rulers  Rulers should be on the plane of the evidence Forensic Science: Fundamentals & Investigations, Chapter 2 7

Sketch the scene 1. Include significant items and ALL evidence – Walls, furniture, trees – Fingerprints, blood spatter, cartridge cases, tire/shoe prints 2. Use two points, stationary if possible, from which to measure each item  Triangulating location 3. A rough scene sketch may be converted to a scale sketch for analysis display Forensic Science: Fundamentals & Investigations, Chapter 2 8

Search for evidence 1. Observe & record systematically  Start at one part of a crime scene slowly look at every part for evidence.  Take contemporaneous notes & photograph. 2. Turn off filters  On a crime scene you will not know what will turn out to be important.  Pay attention to all the details in your surroundings.  Don’t let eyewitness accounts and your own thinking introduce prejudices. Forensic Science: Fundamentals & Investigations, Chapter 2 9

Secure the collected evidence 1. Package appropriately  Do NOT package wet items in plastic  Bags, paper, boxes can be used 2. Seal & sign seal  Maintain chain of custody 3. Submit to lab for analysis Forensic Science: Fundamentals & Investigations, Chapter 2 10

Forensic Science: Fundamentals & Investigations, Chapter 2 11 Packaging the evidence 1. Crease a clean paper and place the evidence in the X position (as shown above). 2. Fold in the left and right sides, and then fold in the top and bottom. 3. Put the bindle into a plastic or paper evidence bag affixing a seal over the opening. 4. Write your name on the seal.

Forensic Science: Fundamentals & Investigations, Chapter 2 12 Chain of Custody 1. Bags the evidence, mark it for identification, seal it, and sign it across the sealed edge. 2. Sign it over to the forensic lab for analysis, the scientist opens it, but not on the sealed edge. 3. After analysis, the scientist puts it back in the evidence bag, seals it, signs the seal, and signs the evidence log. Why do this? What does it prevent?

Forensic Science: Fundamentals & Investigations, Chapter 2 13 Analyze the Evidence The lab results can:  Show how reliable are any witness accounts.  Establish the identity of suspects or victims.  Show suspects to be innocent or link them with a scene or victim.

Forensic Science: Fundamentals & Investigations, Chapter 2 14 Crime Scene Reconstruction Crime scene reconstruction involves: – forming a hypothesis – of the sequence of events – from before the crime was committed – through its commission.

Forensic Science: Fundamentals & Investigations, Chapter 2 15 Staged Crime Scenes When the lab results do not match up with the testimony of witnesses, it can mean the crime was staged. Common examples include:  Staging a fire—to cover bankruptcy.  Staging a suicide—to cover a murder.  Staging a burglary—to collect insurance money.

Forensic Science: Fundamentals & Investigations, Chapter 2 16 Staged Crime Scenes To help determine whether a crime scene was staged, consider:  Whether the type of wound found on the victim matches the weapon employed.  Whether the wound could have been easily self- inflicted.  The mood and actions of the victim before the event.  The mood and actions of a suspect before the event.