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Notes for the Instructor

During a crime, investigators will do two things to get more information from each of the suspects. The first is to have each suspect write a statement, explaining in his own words what he was doing at the time of the crime. Forensic analysts are trained to read these statements for deception or omission of information. They look for subtle changes in language, grammar, sentence structure, and content as signals of questionable information.

Once the investigator has identified questionable pieces of the suspect’s story, the suspect is sat down for an interview. During the interview, investigators are trained question-askers – focusing on inconsistencies or holes in the suspect’s story. Investigators pay attention to what suspects say as well as what they don’t say. They also notice how the suspect holds himself while responding, or his body language. Interviews are often recorded so they can be revisited later and by other investigators.

In the case of The Cookie Jar Mystery, statements have been gathered from each of the four suspects. Students will analyze these statements for deception and missing information. Specifically, students will be looking for instances of:

  • Redirection, or times when a suspect might try to draw attention away from his own actions.
  • Changes in pronouns throughout the story. This can indicate a suspect trying to provide a distance between himself and the story he is telling.
  • Evasiveness, or the brushing aside of important information as if it were minor or irrelevant.

Based on the suspects’ statements, students will need to piece together a storyline of what happened that day. Students should consider:

  • Does this story make sense?
  • Are there any holes or chunks of time unaccounted for in the story?

Sometimes a suspect’s statement and interview contain enough information to convince the police to arrest him for the crime, particularly if the suspect confesses. However, investigators must be careful that a person may confess to a crime for other reasons – perhaps to hide another’s involvement, or to draw attention away from the larger story of what really happened.

Before making any arrests, investigators will see which suspect looks likely to have committed the crime. They will look to see which suspect had:

  • the means, or a way, to commit the crime
  • a motive, or reason, to commit the crime
  • an opportunity, or chance, to commit the crime

These three things help investigators make objective decisions about a suspect’s involvement.

Before going into this lesson, most of the students will already have a good idea of which suspect broke Mrs. Randall’s cookie jar. This lesson is designed to help organize the evidence from each lesson and guide students in the analysis of all the materials and information collected.

The activities in this lesson address Next Generation Science Standards practices of Planning and Carrying Out Investigations and Analyzing and Interpreting Data. In addition, they address Common Core Learning Standards. See the appendix on page 105 for more details.