Direct/Circum. Evidence/Evidence Collection
Define Direct Evidence.
Direct evidence is eyewitness testimony. (ex. You saw Mr. Smith steal the diamond necklace.
What things can be learned from blood spatter?
Type and velocity of weapon, # of blows, handedness of assailant, position of victim during attack, which wounds inflicted first, if death happened right away, what type of injury
Define and give an example of Class Evidence/Explain why it belongs in this category.
Hairs, fibers, soil, paint chips, powders: These can be similar to a source, but not at the exclusion of all other sources. (Thereare many people that have brown hair, that own the same shirt,have yards with similar soil, etc)
b. Blood Type: Thousands of people have Type A+ blood
c. Product brand, make, model, lot, year, etc–Many of the same product are made in each group.
Name 3 Crime scene Personnel and describe their duties at the scene.
A.Police Officer: (first at scene) Isolate and secure the scene,Establish a common approach path.
B. Members of the CSI Unit (Forensic Photographer, Scene Sketcher)
C. Medical Examiner/Coroner-Determine cause of death perform the autopsy if they have medical training, and analyze evidence,determine whether an autopsy is necessary, perhaps provide recommendations for post-mortem examinations such as toxicology tests
Why should the evidence bag be initialed and dated across the tape?
So that if the bag is opened the signature would be skewed, or ripped and it would be obvious the evidence was tampered with.
Define circumstantial evidence.
Circumstantial evidence is indirect evidence that doesn’t prove a fact about the case. (ex. You saw Mr. Smith go into the house, and when he came out, the diamond necklace was gone.)
What type of light is often used to find blood at a crime scene?
When referring to blood spatter, what is the meaning of “The tail tells the tale”?
UV Light
When blood hits a surface/object, the energy from its movement will cause a “tail” to splat out, continuing in the direction of travel.
Define and give an example of Individual Evidence./Explain why it belongs in this category.
a. DNA Fingerprint-Unique to each individual (except for identical twins)
b. Fingerprints- each finger and toe print on the planet is unique!
c. Wear patterns/Impressions-striation/scratch marks on fired bullets, tool marks, wear marks on tires and shoes are statistically unique. ..imperfections during manufacturing, as well as nicks and scratches that occur during the life of the tool.
d. Things that fit together–like a note ripped from a notepad,leaving a matching torn edge.
What are 5 things that must be included in a crime scene sketch?
Case number, date and time, location, arrow to indicate north, sketch artist, evidence numbers, key that correlates to evidence numbers,locations of doors and windows, measurements to center of every piece of evidence, measurements from the center of the victim’s head.
Describe the importance of the Chain of Custody.
It is a written piece of evidence. It seeks to hold individuals accountable for not altering evidence taken from crime scene. If chain is broken, the evidence is often deemed ineligible to be used in court.
Think about a crime scene. Name at least 3 pieces of circumstantial evidence that the suspect may have left at the crime scene, or have taken with him from the crime scene, that could have been used in the investigation instead of direct evidence of the eye witness.
Footprints, hairs, fibers, fingerprints, soil on suspect’s clothing, bruising on the suspect’s face
24. Name one chemical that is applied to blood at a crime scene. Tell what is does, how it reacts and any advantages or disadvantages.
a. Luminol- glows blue in UV light when reacting with hemoglobin in blood, Also reacts with bleach.
b. Fluorescein-Used to find latent blood (smudges, stains, bloody prints) glows green in UV light, also reacts with bleach
c. Leuco Crystal Violet (LCV)-Makes blood evidence easier to see. Used to photograph details (like footprints)Turns purple
Name the 4 different types of photos that should be taken at the crime scene.
Overview shot, midrange, Close up with scale and evidence marker, Close-up without a scale or evidence marker
Name the 4 main steps in processing crime scene .
a. Isolate the scene b. Search the scene c.Document the scene d. Collect the evidence.
What is the job of the arson investigator?
To figure out if a fire was an accident or on purpose. Often times they are called to testify in court as witnesses due to their expertise.
What is the correct method to collect ballistics (bullets)?-
Collected with tweezers and placed in a small bag or box.
What are the 3 types of blood spatter patterns?
a. Passive b. Projected c. Transfer or contact bloodstains
You have just taken a close up photo of a knife with the evidence number and ruler. Why is it also important to take a photo without the number and ruler?
To demonstrate that there is no evidence or important item hiding underneath the scale or number.
Name a crime scene search method and tell when and how it should be used.
A. Spiral–(for large indoor or outdoor areas with few obstacles/one officer starts i center and spirals out, while the other starts on the outside and spirals inward. They pass each other and check over other’s area to be sure nothing was missed.
B. Strip or parallel: (smaller outdoor areas or indoor crime scenes) 2 officers conduct search together, starting at opposite ends of scene and walk in imagined lines of about 2 feet in width. Pass each otherand check over each other’s area
C. Grid: Similar to parallel. (Outdoor or indoor crime scenes that contain a lot of items/debris-where evidence may be hard to find. 2officers conduct search together, one going right to left and the otherup and down. Swap roles and walk over the area again to be sure nothing was missed.
D. Quadrant or Zone: (Small scenes like elevators or bathrooms) Scene is broken into zones, and sometimes further divided. One or more officers is assigned to imagined zones. Once searched, another officer searches zone to be sure nothing is missed.
What is the biggest problem in arson investigations?
What is the role of BMAP (Bomb Making Materials Awareness Program)?
The fact that they are premeditated and most evidence is burned or destroyed
They encourage companies to be on the lookout for suspicious purchases
Name the correct method to collect footwear and tire impressions and blood.
a. Photographs are taken of both 2D and 3D
impressions. Casts are made of 3D impressions
b. blood- Blood and bloody items are dried out and put into porous containers to prevent the loss of evidence to decomposition.
What is backspatter?
What is castoff? What does it look like, and what can it tell us?
Backspatter is when the force of the bullet spatters blood back from the victim towards the gun/ Can hit the assailant
Castoff is blood that comes off of an object/weapon as it is being swung. It looks like a line of blood, drops all in a row. Castoff can show us how many times a person was struck, and the type of weapon used.
What was Edmond Locard’s basic exchange principle of forensic science?
What are two issues or pitfalls in relying on this principle?
“Every contact leaves a trace."
Some objects do not drop/pick up trace evidence–Trace evidence does not remain forever—Evidence shows that an exchange happened, but does not tell us when it happened.
Name 5 things that should be on the evidence label.
Case #, Evidence #, Location/address of scene, Description of evidence, date/time recovered, recovered by whom?
Name 3 things that all bombs have.
Explosive material, a timer/trigger, a method for starting the reaction