ACTIVITY 11-1 CALCULATING TIME OF DEATH USING RIGOR MORTIS

Death: Meaning, Manner, Mechanism, Cause, and Time326

ACTIVITY 11-1CALCULATING TIME OF DEATH USING RIGOR MORTIS

Background:

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.

Objective:

By the end of this activity, you will be able to:Estimate the time of death using rigor mortis evidence.

Materials:

paperpen or pencilcalculator (optional)

Safety Precautions:

None

Procedure:

In pairs, answer the following questions dealing with approximating the time of death based on rigor mortis evidence. Refer to the Rigor Mortis Reference Table in your textbook (Figures 11-8 and 11-9).

Questions:

Part A

Estimate the approximate time of death 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 “ arm curls” with heavy weights. The only place rigor was present was in his arms.

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© 2009, South-Western, a part of Cengage Learning

Death: Meaning, Manner, Mechanism, Cause, and Time 327

Part B

Estimate the time of death 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 50 degrees Fahrenheit. 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 65 degrees Fahrenheit. When the coroner arrived, the man’s body exhib-ited 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 not rigid. 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.




ACTIVITY 11-2CALCULATING TIME OF DEATH USING ALGOR MORTIS

Objective:

By the end of this activity, you will be able to:Estimate the time of death using algor mortis measurements.

Materials:

paperpen or pencilcalculatorRigor Algor Reference Table

Safety Precautions:

None

Procedure:

Working in pairs, answer the following questions using this information:• For the first 12 hours, the body loses 0.78°C (1.4°F) per hour.• After the first 12 hours, the body loses about 0.39°C (0.7°F) per hour.

Example 1: What is the temperature loss for someone who has been dead for 12 hours?

Temperature loss = (0.78°C/hour) x 12 hours = 9.36°C

Example 2: Calculate the time of death if a person has been dead for less than 12 hours.

If temperature loss is less than 12 hours (or less than 9.36°C), then you use the rate of 0.78°C per hour to estimate the time of death.

Temperature of dead body is 32.2°C (90°F). Normal body temperature is 37°C. (98.6°F) 37°C – 32.2°C = 4.8°C lost since death. How long did it take to lose 4.8°C ? 0.78 (°C/hour) x (unknown number of hours) = degrees lost 0.78 (°C/hour) x (unknown number of hours) = 4.8°C lost by body Solve for the unknown number of hours since death occurred: Number of hours = 4.8°C ÷ 0.78 (°C/hour) Number of hours = 6.1 hours Convert 0.1 hours into minutes: 0.1 hour ( 60 (min/hour) = 6 minutes Hours since death = 6.1 hours or 6 hours and 6 minutes

Example 3: Is the time of death more than 12 hours or less than 12 hours?

Recall that if a body has been dead 12 hours or less, the body loses heat at the rate of 78°C per hour. If the body has been dead 12 hours, then 78°C/hour x 12 hours = 9.36°C.




If a body loses 9.36°C, then the person has been dead for 12 hours.

If a body loses more than 9.36°C, then the person has been dead for more than 12 hours.

If they lose less than 9.36°C, then the body has been dead for less than 12 hours.

For each of the following, state if the body had been dead for more than or less than 12 hours based on the number of degrees lost:

1. total loss of 7.9°C 2. total loss of 4.4°C 3. total loss of 11.7°C 4. total loss of 17.2°C 5. total loss of 10.6°C

Example 4: Calculate the time of death if the person was dead for more than 12 hours.

If the body has lost more than 9.36°C, then you know that the victim has been dead for more than 12 hours. Recall that after 12 hours, the body loses heat at a rate of 0.39°C per hour. You need to calculate how many hours beyond the 12 hours that someone died and add it to the 12 hours. Body temperature was given as 22.2°C (72°F).

1. How many total degrees were lost from the time of death until the body was found?

37°C – 22.2°C = 14.8°C2. Since 14.8°C is more than 9.36°C, you know that the body was dead

longer than 12 hours. How much longer? 37°C – 22.2°C = total loss of 14.8°C since death 9.36°C were lost in the first 12 hours 14.8°C lost since death – 9.36°C lost the first 12 hours = 5.44°C lost after the first 12 hours3. Recall that the rate of heat lost after 12 hours is 0.39°C per hour.

You need to determine how many hours it took to lose that 5.44°C. (0.39°C/ hour) x (unknown # of hours) = degrees lost after 12

hours (0.39°C/hours) x (unknown # of hours) = 5.44°C lost after the

initial 12 hours Solve for unknown number of hours: unknown # of hours (x) = 5.44°C ÷ (0.39°C/hour) = 14.8 hours total time to lose 14.8°C or approximate time of death4. First 12 hours there was a loss of 9.36 degrees C 9.36°C Next 14.8 hours there was an additional loss of 5.44˚ C= 5.44°C Therefore, the victim has been dead about 26.8 hours. (or approxi-

mately 27 hours) .8 hours x 60 min/hr = 48 minutes

Questions:

Part A

1. Determine the approximate time of death using evidence from algor mortis. Show your work. Approximately how long has the victim been dead if his body temperature was 33.1°C (91.6°F)?

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2. A body found outside in the winter has a temperature of 33.1°C. Has the body been dead a longer or shorter time than in problem 1? Explain your answer.

3. Approximately how long has the victim been dead if his body tempera-ture was 25.9°C (85.2°F)?

4. What is the approximate time of death if the body temperature was 15.6°C (60.8°F)?

5. What is the approximate time of death if the body temperature was 10°C (50°F)?

6. What is the approximate time of death if the body temperature was 29.4°C (84.9°F)?

7. What is the approximate time of death if the body temperature was 24°C (75°F)?

Part B

Describe the impact on time of death for each of the variables listed below. If you based your time of death estimates strictly on temperature loss to be 10 hours earlier, would you reduce your 10-hour estimate or increase your 10-hour estimate if the body had been: 1. Naked 2. Exposed to windy conditions 3. Suffering from an illness prior to death 4. Submerged in a lake

Further Study:

1. Investigate the procedures used by crime-scene investigators to take accurate body temperature readings.

2. What is the significance of determining the time of death? Why is it so important to crime-scene investigators to take the temperature of the deceased body if the person is already known to be dead?

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ACTIVITY 11-3INSECT STUDY

Objective:

By the end of this activity, you will be able to:Study the behavior and life cycles of insects associated with decomposition.

Introduction:

The blowfly is often the first insect to reach a corpse and lay its eggs. Use Figures 11-17 and 11-18 as references in your study of blowfly develop-ment.

Materials:

Data Table: Insect Study1 lb. cottage cheese or pudding containersraw calf liver (1 lb.)sharp knifewarm (or hot) day (but not windy or too hot!)thermometerplastic kitchen-sized garbage can with a flip topplastic garbage bag lineranother cardboard box to cut up into smaller piecessmall cardboard box large enough to hold the plastic cottage cheese container and fit inside a garbage candigital camera (optional)

Safety Precautions:

Wash your hands after handling the flies.

Procedure:

Part A: Setting up the Fly Incubator

1. Line a plastic kitchen-sized flip-top or swinging-lid garbage can with a plastic liner.

2. Cut up a cardboard box and fold the cardboard pieces in half so that the pieces of cardboard don’t lie flat.

3. Add the folded cardboard to the bottom of the kitchen garbage bag so that the garbage bag is one-third full. This is important because, during the last stage, the larvae will migrate away from the food to a dry area. If you have ample cardboard pieces available, the larvae will have many areas to hide. (Depending on the size of your garbage can, you might want to add an empty box on top of the cardboard pieces to elevate your fly assembly so that you will have easier access to the fly dish shown on the next page.

Part B: Preparing Your Liver Dish

1. Add raw liver in a plastic cottage cheese container.2. Cut some slices into the surface of the liver to make gashes within the

liver to resemble an open wound.




Part C: Obtaining Flies

1. Leave your open liver container in an area where you want to collect flies. The odor of the liver should attract flies within minutes.

2. Collect flies on a warm day. If it is too cold or too windy, flies will not lay their eggs. Avoid taking fly collections on very windy days or very hot days.

3. Leave the liver container in the open area for at least one hour. Place the dish in an area that will not be disturbed by dogs or cats.

4. Look for very small, white clusters of fly eggs on top of the liver.

Part D: Incubation of Fly Eggs

1. Place the liver container and fly eggs into a small cardboard box. Be sure the cardboard box and the plastic liver dish will fit in the garbage can.

2. Allow the flip-top cover of the garbage can to close. This will still allow other insects to enter the dish while keeping some of the odor inside the garbage can.

3. Keep the garbage can in an area that is not in direct sunlight. Because some odor will be given off, place the garbage can in an area where the odor will not present a problem to others.

Part E: Observations and Data Collection

1. Make observations each day and record on your data table until adult flies have emerged.

2. Take a digital photo of the liver container and any organisms near or on the container. Note: Larvae tend to move away from light, so be ready to quickly take pictures when you view your liver dish.

3. Complete the data table as you make your daily observations. Record the date and time of your daily collections. Record the tempera-

Insect study setup.

Liver inside containerin the sun or semi-shade

Liver inside container andinside the box




ture inside the fly incubator (garbage can). Make other observations such as the color, size, and behavior of your insects.

Part F: Report

Option 1

1. Create a PowerPoint presentation of the insects collected on the liver. Include your digital photos taken of the different stages of the insects you observed. If you do not have a digital camera, obtain pictures of the insects from the Internet.

2. Include the name of all insects and correctly identify their stage of development. Indicate the preferred food source for each of the insects.

3. Do not place too many words on each frame.

Option 2

Write an autobiography from the viewpoint of the fly as it develops from an egg into adulthood. Include in your diary:• Physical description of the insect at different stages of development• Physical description of the insect’s environment• Descriptions of when the insect feeds or does not feed• Description of the type of food it is eating• Descriptions of any “travels” or migrations and movements of the

insect• Photos from your digital pictures taken during the study

Your information should be scientifically correct, but feel free to be creative in your insect diary!

Option 3

Prepare a scrapbook from the viewpoint of the insect as it progresses through its different stages. Use the photos from your study. Add notations indicating the:• Physical descriptions of the insect at the different stages of develop-

ment• Physical descriptions of the insect’s environment• Descriptions or comments on the insect’s source of food at different

stages• Descriptions of any “travels” or migrations of the insect

Your information should be scientifically correct, but feel free to be creative with this scrapbook!

Early instar larvae

Pupa

Adult flies

Later instar larvae

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Lear

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ACTIVITY 11-4ESTIMATING TIME OF DEATH USING INSECT, ALGOR, AND LIVOR MORTIS EVIDENCE

Objective:

By the end of this activity, you will be able to:Estimate the time of death using insect, algor, and livor mortis evidence.

Materials:

paperpen or pencilcalculatorRigor Mortis Reference Table: Refer to the tables distributed by your teacher (Figures 11-8 and 11-9)Insect Reference table: Refer to the table distributed by your teacher (Figure 11-7).

Safety Precautions:

None

Procedure:

Working in pairs, answer the following questions.

Questions

1. A naked, male corpse was found at 8 a.m. on Tuesday, July 9. The air temperature was already 26.7°C (81°F). The body exhibited some stiff-ness in the face and eyelids and had a body temperature of 34.4°C (93.9°F). Livor mortis was not evident.

a. Approximately how long ago did the man die? b. Justify your answer. c. Would clothing on the body have made a difference in determining

the actual time of death? Why or why not?2. At noon, a female corpse was found partially submerged on the shore

of a lake. The air temperature was 26.7°C (81°F), and the water tem-perature was about 15.6°C (61°F). Rigor mortis was not evident, and the body’s temperature was 15.6°C. Livor mortis showed a noticeable reddening on the victim’s back that did not disappear when pressed. Bacterial activity was not significantly increased, and the lungs were filled with water.

a. Approximately how long ago did the woman die? b. Justify your answer.3. The body felt cold to the touch. The thermometer gave a reading of

21.1°C (70°F) for the body temperature. No rigor mortis was evident, but livor mortis had set in with blood pooling along the back. There was no noticeable increase in bloating or bacterial activity in the digestive system and no putrefaction. The man had been dead for more than 48 hours. How is that possible?




4. The dead body contained evidence of blowfly infestation. The larvae were collected and reared in a lab in an environment similar to the conditions surrounding the dead body. Adult flies mated and laid eggs. Data was collected, noting the time required to progress from one stage to the other and recorded in the following Data Table.

a. Record the estimated time since death if the insects recovered from the dead body were in each of the stages below:

egg, larva 1, larva 2, larva 3, pupa, adult. b. Record the estimated time since death if insects were in the

following stages: Some eggs and some larva stage 1, some adults and some pupae, some larva found in stage 2 and stage 3.

5. A dead body of an elderly gentleman was discovered in an abandoned building. Blowfly pupae were found on the body. A missing person’s report was filed for an elderly gentleman who had wandered away from home just two days before. The body found was similar in age, height, and weight to the missing person. Could this possibly be the same person as the person described in the missing person’s report? Explain your answer.

6. The police received a report about a body found in the woods behind the local shopping center. The forensic investigator collected 5 differ-ent types of living insects on the man’s body. It’s important to stress that investigators found all 5 insects alive on the body at the same time. The insects were sent to the forensic entomology lab, where they were raised under similar conditions to those found around the dead body. The following chart describes the life cycles of each of the five different types of insects found on the dead body. How long has the man been dead? Justify your answer.

Stage Accumulated Time Since

Egg Was Laid (Hours)

Accumulated Time Since

Egg Was Laid (Days)

Egg Egg laid minutes after death 0

Larva stage 1 24 1

Larva stage 2 60 2.5

Larva stage 3 96–120 4–5

Pupa 192–288 8–12

Adult 432–576 18–24

Day

Insect 1 2 3 4 5 6 7 8 9 10

Blowfly 1 1 1 1 1 1 1 1 1 0

Species A 0 0 0 0 1 1 1 1 1 1

Species B 0 0 0 0 0 0 1 1 1 0

Species C 0 0 0 0 0 0 0 0 1 1

Species D 0 0 0 0 0 1 1 1 1 1

0 = no evidence of fly species; 1 = evidence of egg, larva (maggot) or pupa




ACTIVITY 11-5TOMMY THE TUB

Background:

Whether you are playing volleyball on a hot beach in August or snowboard-ing down a mountain on a cold, windy day in January, your body is con-stantly working to maintain a normal body temperature. Living organisms are equipped with mechanisms that maintain this balance (homeostasis). However, if a person becomes ill or dies, the mechanisms fail.

Objectives:

By the end of this activity, you will be able to:1. Observe and record the heat loss each hour of a simulated human

body, “Tommy the Tub,” over a 24-hour period.2. Compare that heat loss to the projected heat loss of a human corpse.

In this activity, you will create a simulation of a human body and record the heat loss over a 24-hour time period. Because the body is mostly water, you will substitute a tub of approximately the same volume of water as a human body. You are to compare the heat loss of Tommy the Tub to the projected heat loss of 0.78°C (1.4°F) for the first 12 hours and 0.39°C (0.7°F) for the next 12 hours.

Materials:

Activity Sheet for Activity 11-566-L plastic tub (with drawing of body, optional)probe ware interface and two temperature probes or two thermometerscomputer or TI-83 calculator (or better)cart for transporting the tubgraph paper

Safety Precautions:

None

Time Required to Complete Activity:

two consecutive days (30 minutes per day)

Procedure:

1. Fill a tub with approximately 66 liters of hot water, adjusting the tem-perature 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




6. From the probe ware data or your data table, determine the average loss of tub water temperature for the first 12 hours _______°C, aver-age loss of tub water temperature for hours 13 to 24 ________°C, and average loss of tub temperature for hours 1 to 24 ________°C.

7. Prepare a best-fit graph of Tommy’s heat loss over a 24-hour period. Include in your graph:

a. Title of graph b. Appropriate scale for x and y axis c. Labeled x and y axis d. Units on x and y scale e. 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.)

Questions:

1. How does Tommy the Tub’s temperature loss 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 the Tub’s temperature loss 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 the Tub as an appropri-ate 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.

Time (hrs.) Tommy Tub

Temp. (˚C)

Ambient Temp

(˚C)

Time (hrs.) Tommy Tub

Temp. (˚C)

Ambient Temp

(˚C)

0 13

1 14

2 15

3 16

4 17

5 18

6 19

7 20

8 21

9 22

10 23

11 24

12 Average loss per hour



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ACTIVITY 11-1 CALCULATING TIME OF DEATH USING RIGOR MORTIS