click pencil for helle crafts case
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Click pencil for helle crafts case. Unit 2. Determining the manner and time since death. How do police estimate how long a person has been dead WHEN THEY ARRIVE ON SCENE?. Temperature of the body Stiffness of the body . Forensic pathologist . - PowerPoint PPT PresentationTRANSCRIPT
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DETERMINING THE MANNER AND TIME SINCE DEATH
Unit 2
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How do police estimate how long a person has been dead WHEN THEY ARRIVE ON SCENE?
• Temperature of the body
• Stiffness of the body
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• Responsible for examining a corpse in order to determine cause of death
• Record temp of body, temp at scene of crime, weight of victim, etc.
Forensic pathologist
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Livor mortis• Setting of blood in the lower portion of the body that causes a
purplish red discoloration of the skin
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RIGOR MORTIS
• Chemical change in muscles after death that causes the limbs to become stiff
• Caused by a halt in ATP action
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THE EYESEyes develop a thin cloudy film 3 hours after death.
Eyes also become softer due to loss of fluid pressure behind them
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SKIN COLOR
• 48 hours after death, bacteria starts to grow on skin giving it a greenish color.
• Starts in lower stomach area and spreads outwards
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ALGOR MORTIS
Steady decline in body temperature until the body reaches ambient temperature. As body starts to decompose, the temp rises again.
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Fun math part!!!• Estimated body temperature drops at a rate of 0.8K per hour
• To convert kelvin to Celsius, subtract 273.15 from the kelvin temperature.
• Example: A person’s normal body temperature is 310K, convert that to °C.
•• 310K• - 273.15
• ----------------• =37 °C
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• To convert Kelvin to Fahrenheit:
1. Multiply the kelvin temp. by 9/5
2. Subtract 460 from the above number
• THIS YIELDS THE TEMPERATURE IN °F
•Convert 345.5 K to °F
• 345.5 x 9/5= 621
• 621• -460
• _________• = 161 °F
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• °F to °C Deduct 32, then multiply by 5, then divide by 9
• °C to °F Multiply by 9, then divide by 5, then add 32
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• First it’s important to know that human body temperature is 98.6 °F
• Then you can convert from there
• 98.6°F• -32• ______• =66.6• x 5• ________• 333• /9
• =37°C•
What’s human body temperature in °C?
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SO WHY IS ALL THIS IMPORTANT?!?!• Going back to what we said earlier, if we know a person’s body
temperature drops at a rate of 0.8K per hour after death, what would be the temperature of a person that has been dead for 3 days?
• *NEGLECTING EXTERNAL FACTORS*
• 1 day= 24 hours• 3days= 72 hours
• 72hours x 0.8K = 57.6K temp. drop
• So if you know normal body temp is 98.6 °F• = 310 K• 310k- 57.6 K = 252.4 K
• 252.4 K= -5.68 °F• BODY GETS REALLY COLD REALLY FAST!!!
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IMPORTANT TO NOTE!
• The body would never actually get that cold.
• It actually only cools down until it gets to ambient temperature.
• Chemical processes involved with decomposition cause the body to warm back up.