Who Killed the Intruder?


Welcome Forensic Scientist, 

You were all asked here to solve a mystery. We will begin by understanding the different parts of blood. We will utilize different terms such as "Platelets", "White Blood Cells", and "Red Blood Cells". We will also learn how these different parts of blood can help us find the killer of our victim!

It is the Forensic department's job to learn all that you can about the blood, blood spatters, and suspect! Complete each task by reading the material, watching the videos, and answering the questions that follow! After you're done you will be ready to reveal who the suspect really is!


Watch the video and answer the following questions! 

Video: https://www.showme.com/sh/?h=yjUFmUq.  

Blood: What makes up our blood?



Cells in our Blood:

  1. Scientific Name:
    1. Common Name:
    2. Function:
  2. Scientific Name:
    1. Common name
    2. Function:
  3. Scientific Name: 
    1. Common Name:
    2. Function:


 Draw the following:

  1. Red Blood Cells:


  1. White Blood Cells:


  1. Platelets: 


Hemoglobin is a ____________ that is in charge of transporting ____________. 


The average adults has about _________L of blood. 


In 2 to 3 drops of blood you would find about ___________ Red Blood Cells (RBC). 

  • Do RBC have a nucleus? ______
  • Do White Blood Cells have a nucleus? _________
  • Which cell would we gather DNA from in about 2 or 3 drops of blood? ______________


Blood makes up about ___________% of our total body weight. 



You’ve completed all the assignment. For your final assignment, you are figuring out “How to determine the victim when he/she created the blood splatter”.

  • The activity begins with a 911 call: 
    • A 911 call was placed by Joe Murray at 9:30 Pm 
    • Joe said he and an intruder were fighting and he began to strangle him. He said that he reached for a weapon and hit it over the intruder’s head until he collapsed. 
    • When the police arrived at the scene the intruder was dead.
    • Joe said that he hit the intruder with a hammer in the head while he was standing. He said he was strangling him so it was self-defense. 
  • How can you tell if Joe was telling the truth? Was the intruder really standing at the time of the attack. The intruder was hit in the head, and is 6 feet 1 in tall. 
  • (There will be a “scene of the crime” in the classroom) 
  • Find 3-5 inches of blood drops in the blood spatter and determine the Angel of Impact. Then determine the Angel of Impact for each blood spots at the scene of the crime. 
    • Collect data for Blood Spot 1, 2, and 3 
    • Length, width, degree 
    • (Answers will be included in the presentation, but only given after students have collected their own data during the investigation)
    • Show students how they find the Point of Contact for each blood spot (using the lasers, and showing how it is done)

Was JOE telling the truth?!

Students will gather their data and come to the conclusion of whether Joe was telling the truth. If he was not telling the truth about the intruder then students will speculate who they think the intruder was in connection with Joe.

Students will also reflect on how they can figure out who the intruder is.  

Teacher Page

Who really did it?!


The standards utilized for my lesson were: Students in 12thgrade have been exposed to cells and that they contain genetic information from DNA molecules (NGSS). 

This site is intended to be used at home as an assignment. The hope is that students will utilize and see the advantage of the technology inside and outside of the classroom while still learning.