Discover: Searching for Evidence

Every place you go and every person you meet, you leave something behind, and you take something with you. Most of the time you do not even realize this is happening because the items are so small you cannot see them. Things left behind include hair, fingerprints, saliva, fibres from clothes, and skin flakes. You take away hair, fibres, or soils on shoes. Trace evidence is what investigators are looking for to find who might have been at a crime scene.

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However, not all evidence is so small that you need special equipment to see it. Careful observation often reveals evidence of where someone has been. You need only to observe the kind of debris you might see on the person's clothes, observe footprints, tire tracks, tool marks, paint flecks, ink, or oils.

In this activity, you will be examining samples from two different locations. The debris found on these samples may give you some information about where they came from.

What is used in a court of law to convict a suspect can be direct evidence such as witness testimony, written documents, videotapes, media, photographs or indirect evidence such as fingerprints, shoe prints, DNA etc.  Trace evidence is indirect evidence.  It may be physical evidence  (from a non-living source) or biological evidence (from a living source).


  Notebook: What evidence of human activity can you find around your home?

  1. Click here to download this activity. 
  2. Complete the activity and save to your Investigation Notebook. 


  Check Your Answers

    (Answers will vary depending on locations used for sampling.)

    1. Examples:
      • gravel, rocks, dirt suggest a parking lot
      • grass, leaves, twigs, suggest a forest or field
      • carpet fibres, dust suggest floor
    2. Humans: garbage or litter, hair, crumbs, fingernail clippings, etc.
    3. Animals: fur, feathers, hair, droppings

Closer examination or analysis of the footprints or hair would be required. Human footprints would have shoe prints or resemble human feet with five toes. Animal footprints might look like paws, hooves, or bird tracks. Hair would have to be examined under a microscope or magnifying glass and compared to known samples of human or animal hair.

Digging Deeper

Once you have completed the activity, try this!

Construct a visual representation of your findings by taking a photograph of your tape strips and labelling the photo with your observations in a poster or logbook format.

Based on your findings, answer these questions:

  1. Was there evidence that allowed you to tell where the samples came from? What was that evidence?
  2. Was there evidence that suggested human activity? What was that evidence?
  3. Was there evidence that suggested animal activity? What was that evidence?