Tool Marks, Firearms and Ballistics
Forensic Science
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Literacy / Driving Question Board Connections
Nonfiction Science Literacy Resources
Graphic Organizers / Thinking Maps
Driving Question Boards
Multilingual Learner Language Expectations
Chapter 17 Scenario - Tool Marks Link a Chain of Robberies
A young man watches as a family drives away. Assured that no one is home, he goes to the back of the house, where a fence and several trees shield him from onlookers. He removes a crowbar from his duffel bag. After wedging the crowbar between the doorjamb and the door, he gains entry to the home. Ten minutes later, he flees the home, taking money, electronics, and jewelry. The burglar uses gloves to avoid leaving fingerprints.
When investigators arrive, they photograph the pry marks on the jamb and door. After photographing and measuring the pry marks, they take a silicone cast of the tool mark, an impression made by the end of the tool. The doorjamb around the pry marks is cut away, preserved, and labeled as evidence.
Chapter 17 Introduction
Tools simplify everyday living by extending our ability to do work. Simple tools such as crowbars, knives, screwdrivers, and hammers help us handle manual tasks. In the context of this chapter, a “tool” may be something manufactured specifically for these manual tasks, or it can be any object hastily put to use, such as a length of pipe or a wine bottle. Any one of these “tools” can be used and considered as evidence in a crime.
Chapter 18 Scenario - Suicide or Homicide?
Sandra Duyst’s body was found lying on blood-spattered sheets next to a 9-mm pistol in March 2000. Gunshot residue and star-shaped skin tears around the wound indicated a close-range firing contact wound consistent with a suicide. During the autopsy, the medical examiner discovered one entrance wound and two exit wounds. Upon further examination, the medical examiner discovered a second entrance wound and changed the manner of death from suicide to homicide.
Chapter 18 Introduction
Did you ever wonder why police comb an area in search of the gun used in a crime? Why do crime-scene investigators (CSIs) use metal detectors to find spent cartridges? Why is it so important for a medical examiner to recover bullets embedded in a murder victim? These are all ways of collecting firearm evidence that can help link a suspect to a crime scene or to a particular gun—and ultimately, to solve a crime.
In this chapter, you will investigate the following:
Different types of firearms and their projectiles
How firearms fire a projectile
How markings left on projectiles and spent cartridge casings help solve crimes
How firearm examiners and ballistic experts analyze evidence to determine the type of firearm used, the caliber of the projectile, the angle of impact of the projectile, and the trajectory of the projectile
How improvements in technology have helped improve the reliability and validity of ballistic evidence analysis
Unit Standards
What is the NGSS & 3 Dimensional Science Learning and Why is it Important?
Science Practices - Disciplinary Core Ideas - Crosscutting Concepts
HS-PS2-1: Newton's Second Law of Motion
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration. (Cause and Effect)
Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object rolling down a ramp, or a moving object being pulled by a constant force.
Boundary Statement: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.
HS-PS2-4: Gravitational and Electrostatic Forces Between Objects
Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to describe and predict the gravitational and electrostatic forces between objects. (Patterns)
Clarification Statement: Emphasis is on both quantitative and conceptual descriptions of gravitational and electric fields.
Boundary Statement: Assessment is limited to systems with two objects.
HS-PS4-5: Waves and Information Technology
Communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy. (Cause and Effect)
Clarification Statement: Examples could include solar cells capturing light and converting it to electricity; medical imaging; and communications technology.
Boundary Statement: Assessments are limited to qualitative information. Assessments do not include band theory.
Learning Objectives / Career Connections
By the end of this chapter, students should be able to:
Chapter 17
17.1 Identify examples of tools and tool marks and the value of this type of evidence in a crime-scene
investigation.
17.2 Discuss how tool mark evidence analysis has changed in the last 50 years.
17.3 Describe the unique tool mark evidence that tools produce and how the validity of that evidence is
evaluated.
17.4 Identify the three major types of tool marks and examples of tools that produce these types of
marks.
17.5 Describe how to properly photograph, document, collect, and preserve tool mark evidence.
17.6 Discuss how forensic investigators analyze evidence from tools and tool marks to help solve crimes.
17.7 Explain how new technology has improved the reliability and validity of tool and tool mark evidence
by using more objective, measurable analysis.
17.8 Analyze tools and tool marks to determine whether they are consistent with those collected from a
crime scene.
17.9 Cast a silicone impression of suspect tools to determine whether any of the impressions are
consistent with the impression collected from a crime scene.
Chapter 18
18.1 Differentiate between ballistic and firearm evidence and the individual and class evidence each
provides in a forensic investigation.
18.2 Discuss the history of gunpowder, firearms, and legislation related to firearm ownership.
18.3 Explain how forces and environmental factors influence the trajectory of a bullet.
18.4 Identify the different characteristics of firearms and bullets and how this information can be used to
link a suspect to a crime.
18.5 Describe the proper procedures for collecting and documenting firearm evidence at a crime scene.
18.6 Describe the different methods that are used to analyze firearm and ballistic evidence and how to
reconstruct a crime scene based on that evidence.
18.7 Discuss how technology has improved the ability to obtain, compare, analyze, store, and retrieve
firearm and ballistic evidence.
18.8 Determine the trajectory path of a bullet and the location of a shooter based on sketches and
measurements collected from a crime scene.
18.9 Analyze firing pin data to determine whether suspects from a crime scene can be excluded.
18.10 Analyze the caliber, mass, composition, and condition of spent projectiles.
18.11 Calculate the time and distance required for a projectile to hit its target, considering the force of
gravity.
Using ChatGPT to find local Colorado Phenomena
Use the following prompt, adjust accordingly. "I am a high school science teacher looking for a local Colorado phenomena to address NGSS standard (enter standard you are looking for... example HS-LS1-6)"
Career Connections
Connecting what students are learning to careers not only deepens their engagement in school but also helps them make more informed choices about their future. Browse the following related career profiles to discover what scientists really do on the job and what it takes to prepare for these careers. For additional profiles visit your Year at a Glance Page.
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