Criminal Evidence Chapter 3 Processing the Crime Scene

Chapter Objectives Describe the preliminary investigation. Identify types of crime-scene evidence. Summarize the responsibilities of the first responding officer. Explain how to secure and protect the crime scene. continued on next slide

Chapter Objectives Explain how to collect and search for evidence at the scene. Explain how to properly perform a follow-up investigation.

Describe the preliminary investigation. Learning Objective 3.1 Describe the preliminary investigation.

The Preliminary Investigation Responsibilities of officers responding to the scene include: Being prepared to inform superiors of their findings Assisting victims Securing and protecting the crime scene continued on next slide

The Preliminary Investigation Responsibilities of officers responding to the scene include: Apprehending the perpetrator Collecting and preserving evidence Interviewing witnesses Performing other necessary operational functions

Identify the types of crime-scene evidence. Learning Objective 3.2 Identify the types of crime-scene evidence.

Types of Evidence Locard exchange principle Transfer of evidence theory "Every contact leaves a trace." continued on next slide

Types of Evidence Two commonly used classifications Corpus delicti Evidence that establishes a crime has been committed Associative evidence Links a suspect with a crime continued on next slide

Types of Evidence Physical Direct or prima facie Indirect or circumstantial Testimonial Trace Demonstrative

Summarize the responsibilities of the first responding officer. Learning Objective 3.3 Summarize the responsibilities of the first responding officer.

Responsibilities of First Responding Officer Actions en route to the crime scene Alert for possible presence of perpetrators or perpetrators' vehicles fleeing from the scene. continued on next slide

Responsibilities of First Responding Officer Initial actions upon arrival Verify crime has been committed. Conduct a protective search if exigent circumstances determine the need to enter a building. continued on next slide

Responsibilities of First Responding Officer Assist victims and protect witnesses and bystanders. Arrest the perpetrator. Probable cause or an arrest warrant issued continued on next slide

Responsibilities of First Responding Officer Follow-up communication Identification of witnesses and vehicles Briefing investigators and superiors continued on next slide

Responsibilities of First Responding Officer Information included in the broadcast of a flash description Type, location, and time of crime occurrence Number of suspects involved Physical description of those involved Weapons used continued on next slide

Responsibilities of First Responding Officer Information included in the broadcast of a flash description Direction last observed proceeding and time Means of escape Injuries of anyone involved Vehicles used

Explain how to secure and protect the crime scene. Learning Objective 3.4 Explain how to secure and protect the crime scene.

Securing a Crime Scene Define the crime scene area. Request backup to help restrict access to the crime scene and control onlookers. Clear the interior of the crime scene. continued on next slide

Securing a Crime Scene Record actions previously taken at the scene. Restrict access to the scene. continued on next slide

Securing a Crime Scene A scene "walk-through" will be conducted by the investigator to get an overview of the entire scene. A chain of custody will be established for all evidence. Identify resources needed to assist with the investigation.

Explain how to collect and search for evidence at the scene. Learning Objective 3.5 Explain how to collect and search for evidence at the scene.

Evidence Search and Collection Objectives of evidence discovered at the crime scene Determine the facts of the crime. Identify the lawbreaker. Aid in the arrest of the perpetrator. Aid in the criminal prosecution of the perpetrator. continued on next slide

Evidence Search and Collection Phases of crime scene search Surveying the crime scene Documenting with sketches and photographs Recording all physical evidence Searching for fingerprints continued on next slide

Evidence Search and Collection Crime scene search patterns Spiral search method Grid search method Strip or line search method Quadrant or zone search method continued on next slide

Evidence Search and Collection Collect the most fragile evidence first. Search the crime scene a second time after the evidence has been collected. One investigator should be designated as the evidence collector. Mark evidence immediately. continued on next slide

Evidence Search and Collection Court admissibility Legally seized Integrity of chain of custody Properly packaged and marked

Explain how to properly perform a follow-up investigation. Learning Objective 3.6 Explain how to properly perform a follow-up investigation.

Follow-up Investigation Tasks of follow-up investigator include: Contacting the medical examiner Conducting a neighborhood canvass Preparing crime-scene reports continued on next slide

Follow-up Investigation Performance of the follow-up investigation Analyze reports of officers conducting preliminary phases of the investigation. Review official reports. Gather information on family and associates of suspects. continued on next slide

Follow-up Investigation Performance of the follow-up investigation Examine the victim's background. Check police intelligence files to develop potential suspects. Organize police actions, such as neighborhood canvassing, raids, and search warrants.

Chapter Summary The term preliminary investigation is defined as an initial inquiry by officers to establish facts and circumstances of a suspected crime and preserve any evidence related to that crime. Crime-scene evidence is dynamic, and protection and preservation of the scene are crucial. continued on next slide

Chapter Summary The initial response to a call by the responding officer is a critical phase of any criminal investigation. An important function of responding officers is to ensure neither their actions nor actions of others will unnecessarily disturb the crime scene. continued on next slide

Chapter Summary After an investigator has properly documented a crime scene, the actual search must begin. The investigator's duties do not end at the crime scene.