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Bell Ringer 9/16 PowerPoint PPT Presentation

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Bell Ringer 9/16. Place your HW into the appropriate folder. Clear your desk with the exception of something to write with. You have 2 min. According to the text, what are the 3 functions of a forensic scientist? When you are done, bring your sheet up front and get ready for notes.

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Bell Ringer 9/16

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Bell Ringer 9/16

Place your HW into the appropriate folder.

Clear your desk with the exception of something to write with.

You have 2 min

  • According to the text, what are the 3 functions of a forensic scientist?

    When you are done, bring your sheet up front and get ready for notes.

Functions of the Forensic Scientist

  • Analysis of physical evidence

  • Providing expert testimony

  • Furnishing training in the proper recognition, collection, and preservation of physical evidence

Analysis of Physical Evidence

  • Applies the principles and techniques of the physical and natural sciences to the analysis of evidence – uses the scientific method

  • Must be aware of the demands and constraints of the judicial system

  • Scientific procedures and techniques must satisfy the criteria of admissibility established by the courts

Providing Expert Testimony

  • Expert witness: an individual whom the court determines to possess a particular skill of knowledge in a trade or profession that is not expected of the average layperson and that will aid a court in determining the truth of a matter at trial

  • Forensic scientists are expected to explain the techniques used for analyzing evidence and explain the results to the jury

Furnishing Training

  • In order for the analysis of evidence to be relevant – it must be collected and tracked properly from the time it is identified at a crime scene

  • All police officers are trained in basic crime scene procedures to aid in identification, and prevent contamination, of evidence

Determining the Admissibility of Evidence

  • Not all evidence will be admissible in court, this may be due to several reasons:

    • Improper handling/chain of custody

    • Not a ‘generally accepted’ technique for analysis

Frye Standard, 1923 Frye v. United States

  • Court must decide if a questioned procedure, technique, or principles are “generally accepted” by a meaningful segment of the scientific community

  • In practice, this has meant providing experts to testify that the procedure is generally accepted

  • Courts have also taken note of books, papers, and past judicial decisions in this regard

  • Problem: Not flexible when it comes to new techniques

Rule 702

  • Addresses the problem w. the Frye Standard

  • Under this standard, a witness “qualified as an expert witness by knowledge, skill, experience, training, or education” may offer expert testimony on a scientific or technical matter if:

    • 1. the testimony is based upon sufficient facts or data

    • 2. the testimony is the product of reliable principles and methods

    • 3. the witness has applied the principles and methods reliably to the facts of the case

Daubert Standard, 1993Daubertv. Merrell Dow Pharmaceuticals

  • Court decides on the admissibility of science in the courtroom

  • “General Acceptance” is not an absolute prerequisite for admissibility

  • To ascertain the veracity of scientific evidence presented the trial judge should use the following areas of inquiry: (will be on next slide)

Daubert Criteria

  • Technique or theory can be (and has been) tested

  • Technique or theory has been subject to peer review and publication

  • Technique’s potential rate of error

  • Existence and maintenance of standards controlling the technique’s operation

  • Method or theory has attracted widespread acceptance within a relevant scientific community

Additional Important Cases

  • Kumho Tire Co., Ltd. v. Carmichael, 1999

    • Trail judge also determines the admissibility of expert testimony

  • Coppolinov. State

    • Allows the trail judge to admit evidence tested using new scientific procedures so long as they are based on valid principles and techniques

Power of Observation

Video Experiment


A man is on trial for robbing a convenience store, and several witnesses report seeing him at the scene. During the trial, the defense sets up an experiment to discredit the eye-witness testimony. See how you do on this experiment.

Experimental Video

  • While you are watching this movie, count the number of times the team in white passes the ball to each other.

  • Count silently to yourself and make no comments during the movie.

Movie Debriefing

How many of you saw something strange during the movie?


  • Video was made as part of an experiment designed to test people’s “inattentional blindness”

  • In the original study at Harvard, only 42% of the people noticed the gorilla walking through the scene

  • This activity illustrates the unreliability of eye-witness testimony

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

Spot the Difference


  • You’ve discovered a problem with the crime scene photos from a recent case. Someone has tampered with the crime scene. See how many differences you can spot between the two photographs of the same crime scene.

How many differences can you spot?

Did you find 5 differences?



  • You were the principle crime scene investigator on a case two years ago.

  • It is now time for you to testify in court about your findings.

  • The defense attorney challenges the accuracy of your testimony and implies that you observational skills are not so great.

  • If he can show the jury you are not good at spotting details, he might have a chance of getting his client off.

  • It is often the case in real life situations that the credibility of expert witness testimony is challenged.

  • The thoroughness with which they do their jobs is critical.

Can you prove your observational skills are excellent?

Memory Quiz

  • In your notebook, number your paper from 1-10.

  • You will have 10 seconds to memorize the following photograph.

You have 10 seconds to memorize the picture below.

1. What color coffee mug was in the picture?

  • Blue

  • Red

  • Yellow

  • White

2. When was the deadline?

  • Yesterday

  • Tomorrow

  • Today

  • Oct. 19

3. What time was on the clock on the wall?

  • 10:40

  • 7:20

  • 5:38

  • 11:05

4. How many sticky notes were on the whiteboard?

  • 3

  • 6

  • 7

  • 8

5. Which of the following was NOT in the picture?

  • Stapler

  • Printer

  • Trash can

  • Pen

6. What was the name on the plaque on the desk?

  • Steve

  • Brian

  • David

  • Jeff

7. What color was the victim’s shirt?

  • White

  • Blue

  • Red

  • Green

8. How many plants were in the picture?

  • 0

  • 1

  • 2

  • 3

9. Which of the following was on the floor?

  • Coffee mug

  • Plant

  • Cardboard box

  • Backpack

10. Where was the book in the picture?

  • On the box

  • On the desk

  • On the floor

  • Under the body

More fun at:










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