Name ______Blk ______

How Long Have I been Dead… or Your One Dead Dog!!!

Part 1: How fast does a hot dog lose heat?

Using the temperature probes, “LoggerPro”, and the two different sizes of “hot dogs” construct a graph to determine the rate of cooling of the dead hot dogs. You will need to attach your graph to this lab.

  1. Connect three temperature probes to the “LoggerPro” connection device.
  2. After you logon to the computer select the “LoggerPro” software.
  3. You should see three temperatures that are virtually the same.
  4. Click on “Experiment”, then “Data Collection”.
  5. Change the length to 60 Minutesyou have to change both the time and the units.
  6. Change the sampling rate to 60 samples per minute. Then click “Done”.
  7. Click on “Experiment”, the “Change Units” and change the units to °F for each thermometer.
  8. Acquire one large Hot Dog and one normal Hot Dog.
  9. Put probe 1 length-wise into the large hot dog, probe 2 length-wise into the normal hot dog, and leave probe 3 exposed to the air.
  10. Note the time you start.
  11. Begin recording data by clicking the green “Collect” button.
  12. You can move on to Part 2 while you are collecting data.

Part 2: Using Rigor mortis to determine time of death.

Using the chart on pg. 314-315 in your book determine the approximate time of death for each of the following problems. Explain your answers.

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

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

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

4. 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.

5. 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.

Part 3: Using Insects to predict time of Death

Calculating Accumulated Degree Hours (ADH)

Directions: Calculate the estimated time of death for the following situations. Show all work (use the additional paper if needed). Be prepared to mathematically justify your answers to the class. Use the Green Bottle Fly Life Cycle (above) to obtain information about the ADH for this organism. Record your findings and calculations in the following table.

ADH of the Green Bottle Fly
From / To / Temperature (Degrees F) / Hours / ADH (Accumulated degree hour)
Egg / First instar / 70 / 23 / 70 X 23 = 1610 ADH
First Instar / Second instar / 70 / 27
Second instar / Third instar / 70 / 22
Third instar / Pupae / 70 / 130
Pupae / Adult / 70 / 143
Total hours
  1. At 1 a.m. on May 27, a body was found. On the corpse second instar larvae from the Green Bottle Fly were collected. What was the estimated time of death if the average daily temperature for the week was 85 degrees?
  1. Calculate the estimated time of death for problem 1 above except change the average daily temperature to 95 degrees instead of 85 degrees?
  1. A body is discovered. Rigor mortis evidence places the time of death 15-18 hours prior to the discovery of the body. Livor mortis evidence indicates that the body was dead at least 8 hours. If the average daily temperature was given as 80 degrees F, would you expect to find insects at the egg, first instar larvae, second instar larvae, or third instar larvae stage?
  1. A body of a woman was discovered at 6 a.m. on September 28. Her husband is the main suspect in the murder. Police are trying to establish time of death. Her husband was out of the country from September 21 through 22. Insect evidence present on her body is at the pupae stage of the Green Bottle Fly. With the average daily temperatures listed below, is it possible to eliminate her husband as a suspect based on the insect evidence? Show your work. Explain your answer.

Name ______Blk ______

Average Daily Temperatures

Sept 2880

Sept. 2780

Sept.2675

Sept. 2572

Sept. 2470

Sept.2380

Sept 2285

Sept 2190

Sept 2089

Sept 1987

Sept 1882

Sept 1785

Sept 1681

Name ______Blk ______

Part 1 Continued: Using your Graph.

Using Body temperature is an inexact science. If your graph looks like one straight line then we will use the average temperature change as a rule of thumb for hot dog cooling (algor mortis) if it looks like two different straight lines with a connection in the middle we will use one rate of temperature change for one period of time and another rate for the time after that. (Forensic scientists use a temperature drop of 1.4 °F for the first 12 hours and .7 °F per hour there after until the body reaches the surrounding temperature conditions.

  1. Using your graph calculate the average temperature change for both the large and small hot dogs.
  2. Large Hot Dog ______degrees/min
  1. Small Hot Dog ______degrees/min
  1. Using your data…You come to a crime scene and find some dead dogs using your graphs answer the following questions
  2. A large dog has a temperature of 100oF how long has it been dead? ______

B. A small dog has a temperature of 100o F how long has it been dead? ______

C. Who died first, A large dog at 90oF or a small dog at 100o F? ______

D. Who died first, a large dog at 110o F or a small dog at 105oF? ______

3. Don’t forget to attach your Titled Graph!