Today’s Lesson Question: What types of evidence have probative value?

Today’s Objectives Students will be able to: 1)Explain Locard's Principle of Exchange. 2)Distinguish between physical evidence and  trace evidence. 3)Understand why some types of trace evidence have more probative value than others.

Consider this Scenario An eyewitness makes a statement about events that took place during a crime.  Police collect physical evidence at the scene.  For one reason or another, the two types of evidence don't add up.  Which evidence is more reliable?  Isn't trace evidence also subject to interpretation?

Types of Evidence Direct evidence is evidence that proves a fact or proposition directly, rather that by secondary deduction or inference. Eyewitness testimony and a defendant's confession are both "direct" evidence. Indirect, or circumstantial, evidence is a fact that can be used to infer another fact. Circumstantial evidence includes body fluids, fibers, and expert witnesses. For example, a woman is found dead at her home with a fiber on her shirt. Eventually, the fiber can lead to the killer.

The Value of Evidence Watch the video on the Value of Evidence and complete the worksheet. Which evidence has the most probative value? Let’s review The Power of Evidence to determine its probative value.