name: period: forensic science mp3 - weeks 1-3 · chapter 12 vocabulary forensic science:...

Name: __________________________________________________ Period: ____

Forensic Science

MP3 - Weeks 1-3

This package includes work for the next three weeks. This packet needs to be completed and turned in when you return

to school. The following is what is included in the packet.

• Manner of Death Notes

• Review Questions on notes

• Blank page to complete vocabulary foldable (Word, Definition, Picture/Example)

• Tommy, Tammy, Timmy the Tubs Lab (Data and Lab sheet)

• Calculating Time of Death Using Rigor Mortis

• Calculating Time of Death Using Algor Mortis

• Death Scenarios

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Forensic Science: Fundamentals & Investigations, 2e Chapter 12

All rights Reserved Cengage/NGL/South-Western © 2016 1

Chapter 12

Vocabulary


All rights Reserved Cengage/NGL/South-Western © 2016

Introduction

o Death of individual body cells is a slow process that does not occur at the exact moment the heart or brain stops.

o A single definition of death is something experts still debate.

o Establishing a postmortem interval (PMI), which is the time between death and body discovery, has great forensic importance.

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Manner of Death

o Official terms for the manner of death include:

• Natural death

• Accidental death

• Suicidal death

• Homicidal death

• Undetermined

3 Forensic Science: Fundamentals & Investigations, 2e Chapter 12


Cause and Mechanism of Death

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o The cause of death is the reason someone dies.

o The mechanism of death describes the specific change in the body that brought about the cessation of life.

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Forensic Science: Fundamentals & Investigations, 2e Chapter 125 Forensic Science: Fundamentals & Investigations, 2e

Chapter 12


Body Changes after Death

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o Death is a sequence of events that affect some cells sooner than others.

• Stage 1: Stoppage

• Stage 2: Autolysis, or Cell Self-Destruction



Algor Mortis

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o Algor mortis PMI estimates can be accurate for deaths that occurred within the past 24 hours if the corpse has not been subject to unusual heat-loss conditions.• For the first 12 hours after death, the body cools at

a rate of .78°C (1.4°F) per hour.

• After the first 12 hours, the body cools about .39°C (.7°F) per hour until the body reaches the same temperature as the surroundings.

• These rates are an estimate and may vary.



Livor Mortis

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o Lividity first becomes noticeable about 2 hours after death.

o The discoloration becomes permanent after 8 hours.

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Rigor Mortis

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o Rigor mortis usually becomes apparent within 2 hours after death.

o The stiffness progresses from smaller muscle groups to larger muscle groups.

o After 12 hours, the body is at its most rigid state.



Rigor Mortis (continued)

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Rigor Mortis (continued)



Autopsy

o An autopsy is a medical examination to determine the cause and manner of death.

o Clinical autopsies are done for medical research study purposes and foul play is not considered.

o Forensic autopsies are performed when foul play is suspected.

• External examination

• Internal examination

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Stomach and Intestinal Contents

o Within 2 to 6 hours, the stomach empties its contents into the small intestines.

o Within 12 more hours, the food leaves the small intestine.

o Within about 24 hours, the wastes are released through the rectum.



Stages of Decomposition

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Stages of Decomposition (continued)

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o “Rule of Thumb" PMI estimate• Body feels warm and is

flaccid (dead less than 3 hours)

• Body feels warm and is stiff (dead 3-8 hours)

• Body feels cold and is stiff (dead 8-36 hours)

• Body feels cold and is flaccid (dead more than 36 hours)



o Death is a process that involves both individual cell death and organism death. The medical and legal communities have been unable to agree upon a precise definition of death.

o When a person dies, it is important to establish the manner, cause, and mechanism of death. An exact time since death, or postmortem interval (PMI), is sometimes difficult to estimate.

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Summary

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o Shortly after death, the body undergoes algor, rigor, and livor mortis. The rate at which they occur is affected by environmental and physiological factors such as ambient temperature, clothing, body mass, age, state of disease, and burial site (if any) of the body.

o Physical and chemical changes that occur after death, such as bloating, skin marbling, and adipocere formation, are caused by decomposition. The process begins with autolysis of cells, is followed by putrefaction, and proceeds to the total degradation of soft tissues.

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Summary (continued)



o Autopsies are typically performed by medical examiners. During an autopsy, the medical examiner performs external and internal examinations, images various pertinent body regions, removes and weighs organs, and takes tissue and fluid samples from organs, often including the eye, stomach, liver, and brain.

o To estimate a postmortem interval, evidence is compiled from the body, the environment, the autopsy findings, and the person’s social contacts, if necessary. A PMI is never precise because of the many environmental variables and other factors that influence what happens to a body after death.

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Summary (continued)

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Notes

Questions:

1. What does PMI measure?

2. How many official terms of manner of death are there? And explain one of them.

3. Lividity can become noticeable about 2 hours after death this is because blood starts to pool what force causes

the blood to pool at the bottom of the body?

4. There is a general guideline for the time after death and the state at which a body is in rigor mortis what three

factors can influence this timeline?

5. Give an estimate for the time of the death for the following three victims

a. a person is found dead and is still warm however you cannot move his arms

b. a female is found dead feels cold and the body can be moved easily

c. a man is found dead warm and while transporting him his arm falls off the gurney and swings back and

forth

Timmy, Tammy, Tommy the Tubs at home Directions:

During this lab we are trying to see how a body loses temperature overtime. During this lab a tub was placed in a cold

environment and a separate tub was placed out in the open air the following data table shows the three different

temperatures per hour for each of the different places they have been labeled accordingly. Complete the worksheet on

the next page. Steps one through four have been completed for you already, use the following data table to complete

the rest of the worksheet.

For step #7 you will have to graph Tammy Tommy and a real corpse use slide number six from the power points to graph

the temperature for a real corpse.

1. Fill a tub with approximately 66 liters of hot water, adjusting the temperature to about 37°C (98.6°F).2. Connect two temperature probes to a computer or TI-83 calculator to record temperature readings

over an extended period. One probe should record the ambient air temperature. The second probe should be submerged in the tub to record the “body temperature.”

3. Set the probe to measure temperature at one-hour intervals for a 24-hour period.4. Record tub temperatures on the data table.5. From the probe ware data or your data table, determine the average air temperature over the 24- hour

period.

Average air temperature = ________°C

7. Prepare a best-fit graph of Tommy’s and Tammy’s and real human corpses (use 3 different colors) heat loss over a 24-hour period.

Include in your graph:a. Title of graphb. Labeled x and y axisc. Draw the best-fit line (This line is approximated. It will be a straight line that will pass through

some of the points but not necessarily all of them. There will be some points on either side of the line and not on the line.)

Name: _________________________________________________ Date: __________________ Period: ________Tommy, Tammy, and Timmy the Tubs

Procedure:

Time (h) Tammy (°C)

Ambient (°C)

Tommy (°C)

Time (h) Tammy (°C) Ambient (°C) Tommy (°C)

0 13

1 14

2 15

3 16

4 17

5 18

6 19

7 20

8 21

9 22

10 23

11 Average loss per hour12

Tommy –

Tammy –

Real Human –

Questions: 1. How do Tommy and Tammy the Tub’s temperature losses over the first 12 hours compare with that of a

real human corpse? Explain your answer. Include data from your graph or data table to support your answer. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

2. How does Tommy and Tammy’s temperature losses over the next 12 hours (hours 13 to 24) compare with the expected heat loss of a real human corpse? Explain your answer. Include data from your graph or data table to support your answer. ______________________________________________________________________________________________________________________________________________________________________________________________________________________

3. Explain some of the limitations of using Tommy and Tammy the Tub as an appropriate model for a human body. _______________________________________________________________________________________________________________________________________________________

4. How could you design a more realistic model of a human corpse to be used in this experiment?__________________________________________________________________________________________________________________________________________________________________

5. Did the ambient temperature change over the 24-hour period? If the ambient temperature did change, describe its possible impact on the loss of temperature noted on Tommy the Tub.__________________________________________________________________________________________________________________________________________________________________

6. List some variables affecting the rate of heat loss from a human corpse. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Name: _______________________________________ Date: ______________ Period: ________CALCULATING TIME OF DEATH USING RIGOR MORTISBackground:In old detective movies, a dead body was often referred to as a “stiff.” The term refers to the onset of rigor mortis that follows soon after death. In this activity, you will estimate the approximate time of death by analyzing the degree of rigor of the deceased body. Refer to the powerpoint.

Estimate the PMI for the following situations. Explain each of your answers:1. A body was found with no evidence of rigor. ___________ _______________________________________________________________________________________________________________________________

2. A body was found exhibiting rigor throughout the entire body. __________ __________________________

________________________________________________________________________________________

3. A body was found exhibiting rigor in the chest, arms, face, and neck. ____________________

________________________________________________________________________________________

4. A body was discovered with rigor present in the legs, but no rigor in the upper torso. ___________________

________________________________________________________________________________________

5. A body was discovered with most muscles relaxed, except for the face. _____________________________

________________________________________________________________________________________

6. A body was discovered in the weight room of a gym. A man had been doing “biceps curls” with heavy weights. The only place

rigor was present was in his arms. ____________________________________

________________________________________________________________________________________

Estimate the PMI based on the following information:

7. A frail, elderly woman’s body was found in her apartment on a hot summer’s evening. Her body exhibited advanced rigor in all

places except her face and neck. ______________________________

8. A body was discovered in the woods. The man had been missing for two days. The average temperature the past 48 hours was

10°C. When the body was discovered, it was at peak rigor.

___________________________________________________________________________________

9. An obese man was discovered in his air-conditioned hotel room sitting in a chair in front of the television. The air conditioner was

set for 18.3°C. When the coroner arrived, the man’s body exhibited rigor in his upper body only. ____________________________

10. While jogging, a young woman was attacked and killed. The perpetrator hid the body in the trunk of a car and fled. When the

woman’s body was discovered, rigor was noticed in her thighs only.

__________________________________________________________________________________

11. The victim’s body is completely stiff. How long has she been dead? Explain your answer. _______________

________________________________________________________________________________________

12. The body is completely stiff. How long has he been dead? Explain your answer. _____________________

________________________________________________________________________________________

13. The victim was found in a snowbank alongside a road. His body is rigid. How long has he been dead? Explain your answer,

remembering the cold temperature. _______________________________

________________________________________________________________________________________

14. The body of the runner was found in the park one early, hot summer morning. Her body shows rigor in her face, neck, arms, and

torso. How long has she been dead? Explain your answer.

_____________ ___________________________________________________________________ Over

Part 2: Calculating Post Mortem Interval (PMI) Using Algor Mortis

Normal Body Temp: 37°C. Body Loses: 0.78°C per hour for the first 12 hours

0.39°C per hour after the first 12 hours

Part A: Determine the approx. PMI (time) using evidence from Algor mortis. Show your work!!

1. Estimate the PMI is the victim’s body temperature at the crime scene was 33.1°C

2. If you discovered that the body in question 1 was found in an air-conditioned room, would that variable increase or decrease your estimated PMI?

What would the new PMI be?

1. Approximately how long has the victim been dead if his body temp. was 25.9°C?

2. What is the approximate PMI if the body temperature was:1. 15.6°C

2. 29.4°C

Part B: If based your PMI estimate of 10 hours solely on temperature decrease, would you reduce or increase your 10 hour estimate if the body had been?:

1. Naked _______________________

2. Exposed to windy conditions _______________________

3. Suffering from illness prior to death _______________________

4. Submerged in a lake _______________________

Forensics Activity: Death Scenarios Objectives: 1. Determine cause of death, mechanism of death, and manner of death from descriptions of events. 2. Create a scenario to illustrate cause of death, mechanism of death, and manner of death. Procedure:

• Read the following scenarios and determine the cause of death, mechanism of death, and the manner of death in each.

• Place your answers to the questions on loose-leaf paper Background: When a death occurs, a physician or medical examiner must fill out a death certificate. In order to properly complete this document, they must determine three things: the cause, the mechanism, and the manner of death. There is often confusion about which is which. The cause of death is the disease or injury that produces the physiological disruption inside the body resulting in death, for example, a gunshot wound to the chest. The mechanism of death is the physiological derangement that results in the death. An example of a mechanism of death due to the gunshot wound described above is exsanguination (extreme blood loss). Last but not least, the manner of death is how the death came about.

Manner of death can be classified in six ways:

1) Natural 2) Accident 3) Suicide 4) Homicide 5) Undetermined 6) Pending

Scenario 1 An elderly woman in her mid-70’s was walking to the local drugstore. On her way, a man shoved her as he walked by and stole her purse. She was not injured in the altercation but was clearly shaken up. About 10 minutes later, she began to experience shortness of breath and chest pain. She was taken to the emergency room. While she was being examined, she developed an irregular heartbeat and died. Questions: 1. What is the cause of death? 2. What is the mechanism of death? 3. What is the manner of death? 4. Should anyone in the scenario be charged with murder? Why or why not?

Scenario 2 Laura was babysitting for her neighbor’s two-year-old and had just put little Justin down for a nap. As she was sitting n the living room texting her friends about the movie they had planned to see later in the evening, she heard the sound of braking glass. Laura grabbed a baseball bat that was propped up in the corner and went to investigate. As she rounded the corner to the kitchen, she noticed broken glass from the door. When Laura turned around, she saw the intruder coming toward her, wielding a very large knife. To her surprise, she raised the bat and crushed his skull. Laura called 911, and police and paramedics responded within minutes. Unfortunately for the intruder, it wasn’t fast enough and he died before they arrived. Questions: 1. What is the cause of death? 2. What is the mechanism of death? 3. What is the manner of death? 4. Should anyone in the scenario be charged with murder? Why or why not? Scenario 3 Devin (age 17) and Carlos (age 16) were known around the neighborhood as “future Felons” because of their frequent run-ins with the law. One afternoon, they decided they wanted to run the local drug dealer out of business and take over his clientele. In order to accomplish this, the boys needed money. So they came up with a plan. The next evening, Devin and Carlos put on dark clothing and ski masks and broke into the corner drugstore about an hour after closing. Neither of them was aware of a night watchman, so when Mr. Hernandez surprised them, Devin, who was carrying a gun, accidently shot and killed Mr. Hernandez. Frightened, both boys fled the scene. When the pharmacist arrived the next morning, she found Mr. Hernandez lying in a pool of blood in front of the prescription counter. Questions: 1. What is the cause of death? 2. What is the mechanism of death? 3. What is the manner of death? 4. Should anyone in the scenario be charged with murder? Why or why not?

Scenario 4: Create a scenario.

name: period: forensic science mp3 - weeks 1-3 · chapter 12 vocabulary forensic science:...

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