The postmortem interval (PMI), also known as time since death, refers to the time between death and the examination of the body. There are several methods that can provide an estimated PMI range, including algor mortis (cooling of the body), rigor mortis, hypostasis, insect activity, and biochemical changes. No single method can precisely determine time of death, but considering circumstances and multiple lines of evidence can offer an educated PMI range, with shorter intervals providing a narrower range than longer intervals after death. The document outlines various signs and their timelines that may indicate PMI.

1. POSTMORTEM
INTERVAL
Mr. Riyaz Khan
VI th Semster
Dept. of Forensic Medicine & Toxicology,
NGMC, Kohalpur

2. The interval between death and the time of examination of
a body is known as postmortem interval (PMI).
Also known as Time Since Death (TSD)
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3. Methods for estimating the postmortem interval first done
by the ancient Greeks and Egyptians during the fourth and
third centuries. They understood that dead bodies cooled
and became stiff over a period of time after death.
a) Warm and not stiff: Dead not more than couple of hours
b) Warm and stiff: Dead between a couple of hours and a
half day.
c) Cold and stiff: Dead between a half day and two days
d) Cold and not stiff: Dead more than two days
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4. It is an important component of medicolegal investigations.
It helps in both civil and criminal cases.
In civil cases, the time of death might determine who
inherits property or whether an insurance policy was in
force.
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5. In criminal cases,
1. To know when the crime was committed.
2. It gives the police a starting point for their inquiries,
and allows them to deal with the information available
more efficiently.
3. It might enable to exclude some suspects and the
search for the likely culprits started earlier
4. To confirm or disprove an alibi
5. To check on a suspect’s statements.
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6. First, all available history should be taken, and then local
physical or environmental factors at the scene of crime,
such as presence of fires and domestic heating, open
windows, atmospheric temperature, etc. must be noted.
The range of time provided is at best an educated guess,
based on knowledge and experience and subject to error.
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7.  Change in the eye
 Algor mortis
 Hypostasis
 Rigor Mortis
 Putrefaction
 Adipocere
 Mummification
 Skeletonization
 Insect activity
 Stomach & Intestinal
Contents
 Contents of urinary
bladder
 Bone marrow Changes
 Biochemical changes
 Circumstantial evidence
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8. When a dead body is still warm, not rigid, without any
permanent haziness of cornea, the death of person
possibly has occurred
 1 hour in summer &
 Within last 2 hour in winter.
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9. Cooling of dead body.
The most useful single indicator of the PMI during the first
24 hour after death.
Under ideal conditions, the body will have no drop in
temperature for 60-90 minutes after death followed by
cooling at the rate of 0.5 OC per hour.
The body attains environmental temperature in about 16-20
hour after death.
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10. Measurement of body temperature by- Thanatometer
Inserted 8-10 cm in rectum and left for 2-3 mins
Other sites auditory meatus, nostrils or under liver.
Calculated by: Thumb Rule
PMI = 98.6 OF – rectal temperaure(F) / 1.5
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11. The extent of appearance and its fixation give some idea
about the time which has passed after death.
Begins immediately after death but
visible after ½ to 1 hours
well developed 4-5 hours
maximum 6-12 hours
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12. Appearance, distribution or its passing away are the most
imp physical changes which are taken into account for
estimation of PMI.
In tropical countries,
begins 1-2 h
develop from head to toe 9-12 h
In temperate countries,
begins 3-4 h
fully established 8-12 h 12

13. Among the delayed changes after death (& after rigor
mortis), this change is the single best one for the purpose of
estimation of PMI.
1. Greenish discoloration
In summer 12-18 h
In winter 24-48 h
2) Marbled appearance 24-36 h
3) Formation of foul smelling gases 18-36 h
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14. Shortest recorded
period in winter is
3 days 22hrs and
in summer 3
weeks
Whole body gets
converted to
adipocere in 1
year.
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15. Complete
mummification
requires at least 3
months to 1 year
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16. Uncoffined bodies
1 year
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This skeleton is of an adult man who had been
missing for 1.5 months during the late fall in the
southeastern united states. He was found in a
wooded area. Although the skeleton was mostly
intact, gnaw marks were evident on several ribs.

17. Flies lay eggs 18-36 hrs
of death
Maggots or larva appear 48-72 hrs
of death
Pupae develop 4-6 days
Adult flies develop 6-10 days
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18. Average meal last for 2-3 hrs
Vegetable meal 4-6 hrs
Farinaceous meal 6-7 hrs
If the stomach is full and contains undigested food, it can
be said that death occurred within 2-4 hours of eating of
the last meal and if the food is digested(indistinguishable),
then >4 hrs.
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19. The amount of urine in the bladder may give some
indication of the time of death in some cases.
If a body is found in the morning with the bladder full, then
inference may be drawn that he might have died before the
usual time of leaving his bed, since the first activity in the
morning after leaving the bed is evacuating the bladder.
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20. nuclei of the neutrophils in marrow start swelling
within 1 hr
Round nuclei 4-5hrs
outline of the neturophils lost 10-12 hrs
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21. a. Cerebrospinal fluid(CSF)
 Amount of potassium increases at a constant rate in relation to
temperature of the body during the first 20 hours.
b. Blood
• There is progressive rise in lactic acid level by 50-75 fold in 12
to 24 hours
• Amino acid nitrogen is less than 14mg/dL upto 10 hours but rises
to 30mg/dL by 48 hours
• Acid phosphatase increases 20 times by 48 hours
• Amylase increases 3-4 times on second day
c. Vitreous Humor:
 Potassium concentration at the time of death is 5-8mmol and
rises at 0.17-0.238mmol/1 hour. 21

22. 1. Facial Hair
Rate of growth of hair after shaving is 0.4mm/day.
Hair does not grow after death.
If the time of his last shave is known, then the time since
death can be calculated.
2. Nails
Rate of growth of nails is 0.1mm/day
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23. Pocket articles like letters, diary, cinema-show ticket, etc
may indicate in some way the date and time upto which the
person survived.
Degree of coagulation of milk, staleness of food on a table
and when the neighbor saw the person etc. may be
valuable.
The dress should be noted as regards to whether the person
is fully dressed or in the night dress.
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24. In some cases, the wrist watch may stop and thus may
indicate the date and exact time of death.
Some idea about the earliest period of death can be made
from the newspaper present by the side of the dead body.
If a body is lying on the grass, it becomes pale due to non-
exposure to sun for about 5 days.
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25. The exact time of death cannot be fixed by any method,
but only an approximate range of time of death can be
given, because there are considerable biological variations
in individual cases. So Never give a single estimate of the
time since death.
The longer the postmortem interval, the wider is the range
of estimate, i.e. the less accurate the estimate of the
interval.
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