Category Archives: Forensic Medicine

Danbury Tremor

Question and Answer on Danbury Tremor

Question 1- What is Danbury tremor?
Answer- Danbury tremor or Danbury shakes is seen in the case of Mercury Poisoning.

Question 2- What is Mercury?
Answer- Mercury is a heavy metal with known toxicity. Mercury is sometimes called quicksilver. It is a heavy, silvery-white liquid metal.

chemical properties of Mercury (part of Periodic Table of the Elements imagemap)

Mercury is the only elemental metal that is liquid at room temperature.

Question 3- What is “Danbury” in Danbury tremor?
Answer- Danbury is a city in Fairfield County, Connecticut, United States, located approximately 50 miles northeast of New York City, making it part of the New York metropolitan area.

Question 4- What is the reason behind adding the name of city of Danbury in “Danbury tremor”?
Answer- Danbury is a city which was earlier popular for hat production. And due to tremendous production of hats, this city was started to name as “Hat City”. Although Danbury’s hat-making industry dated back to 1780, advances in the mechanization of manufacturing processes contributed to its rapid growth in the mid-19th century as did consumer demand for felted fur hats. During the lots of production of hats,(mercury was involved in processing) worker suffered from the tremor which was named as “hatter’s shakes”. which was known as Danbury Tremor afterwards. 

Question 5- Danbury tremor is seen in which type of poisoning?
Answer- Mercury poisoning.

Question 6- What are the other names of Danbury tremors?
 Hatter’s shakes,
 Glass blower’s shakes,
 Intention tremors or
 Shaking palsy.

Question 7- What are other compounds or chemicals that can cause tremors?
Answer- Following Compounds can cause Tremors:

— Alcohol,

— Phosphorus Salts,

— Carbon Monoxide,

— Anti-depressants,

— Phenothiazines,

— Caffeine,

— and, Theophylline, etc.

Question 8- Danbury tremor is first seen in which body part?
Answer- Danbury shakes were first starting with hands then progresses to lips, tongue, arms, and legs.

Question 9- What is the most severe form of tremor in Mercury Poisoning?
Answer- Concussion Mercurilis.

Question 10- What are the other specific diseases related to mercury positioning?
 Mercurialentis: Brown reflex of the anterior lens capsule of the eye which can be seen by Slit-lamp examination.
 Acrodynia or Pink disease: are mostly in children having pinkish acral rashes
 Minamata disease: caused by Organic Contamination like eating fish. It causes disturbances in hand coordination, gait, speech, etc.

 Question 11- What is the common drug treatment for mercury poisoning?
Answer- Treatment of mercury intoxication is with penicillamine or succimer.

N-acetyl penicillamine is the chelator agent along with DMPS may improve the neurological conditions. 

Type of Skull Fracture

Skull Fracture

A skull fracture is any break or damage in the cranial bone (also known as the skull) because of an impact or a blow to the head. There are several types of skull fractures. some of them are given below:

1. Linear Fracture

Linear fracture results from low-energy blunt trauma over a wide surface area of the skull. It runs through the entire thickness of the bone and, by itself, is of little significance except when it runs through a vascular channel, venous sinus groove, or a suture. In these situations, it may cause epidural hematoma, venous sinus thrombosis and occlusion, and sutural diastasis, respectively.

The impact to the sides of skull or vertex –> fracture line is usually in coronal plane. 
The impact to front or rear of skull –> fracture line is usually in sagital plane.

Subtype of Linear Skull Fracture

Hinge Fracture

A common linear base of skull fracture passes across the floor of the middle fossa, often following the petrous temporal or greater wing of the sphenoid bone into the pituitary fossa.

Separate the base of the skull into two halves. Usually being caused by a heavy blow on the side of the head

Diastatic Fracture

These are fractures that occur along the suture lines in the skull. The sutures are the areas between the bones in the head that fuse in young age. In this type of fracture, the normal suture lines are widened. These fractures are more often seen in newborns and older infants.

2. Depressed Fracture

Requires enough heavy force.

Fractures usually start at point of impact.

Object which area is less than 16 cm2 can cause depressed fracture with recognizable shape of the object.

Pond Fracture

In infant, pond fracture is common. it is also known as Ping Pong skull fracture.

Ping pong skull fracture or pond skull fracture refers to a depressed skull fracture

Pond fracture = a shallow depressed fracture forming a concave pond.

Spider’s Web Fracture

If the object is wider, it can cause “Spider’s web fracture”

Spider’s web fracture = a circular fracture at point of impact with radiating fracture from the center


 3. Ring fracture

These occur in the posterior fossa around the foramen magnum, particularly following a fall from a height (with primary ‘feet first’ impact), where the kinetic energy transfer is transmitted up the cervical spine.

Hair analysis

General characteristics of Human Hair

1Colour:White, blonde, light brown, gray brown, dark brown, gray, black, auburn, red.
2Reflectivity:Opaque, gray, translucent, transparent, auburn, clear.
3Length:Fragment, 1”, 1-3”, 3-5”, 5-8”, 8-12”, 12-18”, 18-30”, segment.
4Diameter:20-30 um, 30-40 um, 40-50 um, 50-60 um, 60-70 um, 70-80 um, 80-90 um, 90-100 um, 100-110 um.
5Spatial Configuration:Undulating, kinky, curly, wavy, curved, straight, sinuous
6Tip:Singed, uncut, tapered, rounded, sharp cut, cut at angle, frayed, split, crushed, broken.
7Base:Cut, damaged, pigmented, clear, enlarged, tapering, broken.
8Root:Stretched, absent, bulbous, sheathed, atrophied, follicular, wrenched.
9Cross-section:Polygonal, oval, round oval, undulating, round.
10Pigment:Absent, non-granular, granular, multicolour, chain, massive (clumped), dense, streaked, opaque.
11Medulla:Absent, sparse, scanty, fractional, broken, globular continuous, irregular, double, cellular.
12Cortical fusi:Absent, few, abundant, bunched, linear, central, periphery, roots.
13Cortical cells:Brittle, damaged, fibrous, cellular, invisible, fusiform, ovoid bodies.
14Cosmetic Treatment:Bleached, rinsed, natural, dyed, damaged.
15Cuticle:Ragged, serrated, looped, narrow, layered, wide, cracked, absent, clear, dyed.
16Scales:Flattened, smooth, level, arched, prominent, and serrated.

 Morphological Characteristics of Human Hair for Racial Determination

Negroid60 – 90 umFlatDense & clumpedPrevalent
Caucasoid70 – 100 umOvalEvenly distributedMediumUncommon
Mongoloid90 – 120 umRoundDense AuburnThickNever

 General characteristics of Human Hair from Different Sites

ScalpHead hair, 100 – 1000 mm long, 25-125 um diameter, 0.4 mm/day growth; small root, tapered tip, little diameter variation, various medullation, often with cut tips, may artificially treated.
PubicPudental, 10 – 60 mm long, coarse diameter and prominent diameter, variation and buckling, broad medulla, follicular tags common, asymmetrical cross section twisted and constricted, may be straight, curved or spirally tufted.  
VulvarSecondary pubic hair, finer and shorter than pubic hair, may be abraided.  
ChestPectoral, moderate to considerable diameter variation, long fine arch-like tip, usually longer than pubic hair.
BeardFacial hair, very coarse, 50-300 mm long, large root, irregular structure, often triangular cross section, complex medullation, blunted or razor cut tips, grows 0.4 mm/day.  
AxillaryArm pit, 10-50 mm long, grows 0.3 mm/day, coarse, blunt tip, abraided or frayed, usually straighter than pubic hair, many cortical fusi, sometimes yellowed and bleached.
EyebrowSuperciliary, 1 cm long, 0.16 mm/day growth, curved, relatively coarse for length, smooth curve with punctate tip and large medulla.  
EyelashCiliary, less than 1 cm long, short curved pointed hair.  
LimbLeg and arm hair, 3-6 mm long, fine tips, irregularly medullated, often indistinctly, slightly pigmented.  
EarTragi, pinnae, down  
ButtocksAnal hair, short blunted and abraided hair.  
NoseSimilar to facial hair.  

General Differences between Human Hair and Animal Hair

FeatureHuman HairAnimal Hair
ColourRelatively consistent along shaftOften showing profound colour changes and banding
CortexOccupying most of the width of shaft greater than medullaUsually less than width of medulla
Distribution of pigmentEven, slightly more towards cuticleCentral or denser towards medulla
MedullaLess than one-third width of shaft. Amorphous, mostly not continuous when presentGreater than one-third width of shaft. Continuous, often varying in appearance along shaft, defined structure
ScalesImbricate, similar along shaft from root to tipOften showing variation in structure along shaft from root to tip

Wounds / Injuries

By @forensicfield


A wound is any damage or break in the surface of the skin.

Production of wound: A wound is produced when the intensity of the applied force to the body exceeds the capability of the tissue to adapt or resist the force.

According to section 44 of Indian Panel Code “An injury is define as any harm, whatever illegally caused to any person in body, mind, reputation or property.”

Classification of Injuries

Depending upon Medical

Mechanical Injuries
• Due to Blunt Force
– Abrasions
– Bruises/ Contusions
– Lacerations
– Fracture and dislocations
• Due to Sharp Force
– Incised wounds
– Chop wounds
– Stab Wounds
• Due to Firearms

Thermal Injuries
Due to Cold
–Trench Foot
–Immersion Foot
•Due to Heat

-Radioactive material

Depending upon Gravity (Legal)
-Simple Injury
-Grievous Injury

Depending upon time of Infliction

Depending upon the manner of Inflcition
• Homicidal
• Accidental
• Defence wounds
• Self-inflicted/ self suffered
• Fabricated Fictitious injuries



Wound can be caused by mechanical forces having an impact on A tissue. When A mechanical force acts on A tissue and causes. Lacerations and contusions are examples of mechanical injury inflicted on A living tissue.


Chemical agents can cause tissue wounds by necrosis of the skin such as in snake bites, burns of the skin due to acids or by strictures of the esophagus as a result of drinking concentrated alkalis especially in children (a common household accident).

Radiant agents of tissue injury

Radiation could be in various forms such as X-rays, atomic energy, heat, high voltage electricity and intense cold.

Pathogenic Microorganisms

The pathogens make use of chemicals known as toxins which help to dissolve tissue and can cause hypersensitivity reactions. These organisms do not directly cause wound but invade an already existing wound.


Types of Wounds
  1. Open wounds
  2. Closed wounds
  3. Contusion (Bruise)
  4. Laceration
  5. Avulsions
  6. Punctures
  7. Penetration
Open wounds

These are wounds in which there is loss of superficial surface covering the tissue such as loss of skin.

Closed Wounds

These are wounds that occur without a loss of superficial surface covering the wound. The wound occur under the surface of the skin without affecting the skin. An example of this type of wound is contusion. Infection of these wounds is rare and it may resolve without any treatment if it is not extensive.


In this type of injuries the skin in which the outer layer of the skin is scarped off. Examples of the abrasions are scratches, grazing of the skin caused by dragging, imprint caused by belt/hunter/ sticks.


This type of injuries occurs when blood vessels in the skin or internal organ are ruptured. A bruise heals by destruction and removal of the extravasated blood.


Lacerations are tears or splits of skin, mucous membranes, muscle or internal organs produced by application of blunt force or broad are of the body. Types of lacerations are split lacerations (crushing of the skin between two hard objects), stretch lacerations (overstretching of skin), avulsion, tears etc.

Sharp Force Injury

These are caused by cutting or stabbing the skin with sharp instruments/weapons such as knives, swords, tins, broken glass bottles, razor blade and tools.

a) Incised/cuts Injury: This type of wound is a superficial injury in which the size of the injuries on the surface is larger than the depth.

b) Stab or Penetrating Injury- This type of injury is produced from the penetration of pointed or sharp weapons on to the depth of the body that is deeper than its length, generally knives.

Firearms Injury

They are usually recognized without difficulty. The injuries produced by fire arms vary depending on the projectile, the muzzle velocity, distance, angle of firing and part of the body involved. These wound are subdivided as, when a bullet, passing through a body, produces a wound. the point of entrance on the skin known as ENTRY WOUND and another at the point of exit of the bullet known as EXIT WOUND.


 It is the breach of continuity of bone or tooth caused by application of blunt force. Clinical features and X-ray findings are considered to diagnose this type of lesion. In dislocation of joint the bone ends get displaced completely from their normal anatomical positions with damage to the adjacent tissues.

Incised wound

 It is caused by the sharp edge of the weapon applied to the skin perpendicularly or obliquely making regular clean edges of the wound. It is called a slash wound when the length of the wound is greater than its depth.

Blast wounds

These are produced by explosion of bombs and are due to blast pressure wave (shock wave), blast winds, heat, splinters, shrapnels, surrounding small fragments propelled by blast winds.


Burns are caused by flame, heated objects and scalds by hot liquids and vapours or gases.

Bodily harm may also be caused by corrosives, electricity, insecticide, high dose of drugs.

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Post-Mortem Interval (PMI)

By @forensicfield

Many types of changes to a body occur after death. Some of those that can be used to determine the post-mortem Interval are –

  • Change In The Eye
  • Algor Mortis
  • Hypostatis
  • Rigor Mortis
  • Putrefaction
  • Adipocere
  • Mummifiication
  • Stomach & Intestinal Contents
  • Skeletonization
  • Insect Activity
  • Contents Of Urinary Bladder
  • Bone Marrow Changes
  • Circumstantial Evidence

Changes can also differentiate in following stages:-

The changes which take is may be helpful in estimation of the approximate time of death and the sign of death appear in the following order :-

I.     Immediate Changes

  1. Insensibility
  2. Cessation Of Respiration
  3. Stoppage Of Blood Circulation

II.     Early Changes  

  1. Loss Of Elasticity
  2. Change In The Eye
  3. Algor Mortis
  4. Flaccid Of Muscles
  5. Postmortem Lividity
  6. Livor Mortis

III.    Late Changes

  1. Putrefaction
  2. Adipocere Formation
  3. Mummification


These Stages Of Post-Mortem Changes Are::

Stage 1 – Fresh Stage
Stage 2 – Bloated Stage
Stage 3 – Active Decay Stage
Stage 4 – Post Decay Stage
Stage 5 – Skeletonization

Fresh Stage

This stage starts from the moment of death to the first signs of bloating of the body. The first organism to arrive are the blowflies (Calliphoridae).

Livor mortis

Cessation of circulation and loss of muscles tone after death allows blood within vessels to settle under gravity, producing a pink or purple colour in those areas of the body that are lowest or dependent.

Hypostasis  was maximal /  fully developed after about 12 hours.

Rigor mortis

  • Rigor mortis is a temperature dependent physiochemical phenomenon that occurs in muscle cells following cessation of a supply of oxygen.
  • Rigor mortis develops at the same time through out the body, but it is detected more rapidly in small muscles such as around eyes and mouth.

Algor mortis (post mortem body cooling)

A Body Cools After Death According To Old Rule. Body Temperature Falls By 1.50F (210C) Per Hour. The Rate At Which A Body Cools After Death Depends On The Following-

  • Mass Of The Body,
  • Surface Area Of The Body,
  • Body Temperature At The Time Of Death (370C Is Used As Expected Temperature),
  • Site Of Reading Of Post Mortem Body Temperature,
  • Posture Of The Body,
  • Clothing And Coverings,
  • Obesity (Fat Insulates),
  • Emaciation,
  • Environmental Temperature.

Bloated stage

Breakdown of the body continues because of bacterial activity, or putrefaction and this is the easiest stage to distinguish. Gases causing the corpse to bloat are generated through metabolism of nutrients by anaerobic bacteria.

Initially the abdomen swells but later the whole body becomes stretched like an air- balloon.

At this stage more and more blowflies are attracted to the body, possibly in response to the smell of the breakdown gases.

Active Decay Stage

This stage is recognizable by the skin of the corpse breaking up and starting to discard from body.  The removing of skin allows the decomposition gases to escape and so the inflation of the body gradually subsides as putrefaction continues.

Decomposition / Putrefaction

Dead Bodies Are Eventually Breaking Down Into Their Constituents Components.

Soft Tissues Degrade And Liquefy Over A Period Of Time, The Rate Of Progress Of Which Is Temperature Dependent. The Warmer The Environment In Which The Body Lies, The More Rapid Liquefaction Occurs.

Dead Bodies Degrade At Different Rates Depending Upon The Medium In Which They Are Placed- Immersion In Water Slows The Process, While Burial Slows The Rate Even More.


When a body lies in dry condition it may desiccate instead of putrefying, a process called mummification.

Mummified are dry and leathery and often brown in color.

Mummification commonly occurs in warm and hot climates, such as desert.

Post-Decay Stage

In the later stages of decay, all that remains of the body are skin, cartilages and bones with some remnant of flesh including the intestines.

Any remaining body tissue can be dried. The biggest indicator of this stage is an increase in presence of beetles and a reduction in the dominance of the flies (Diptera) on the body.


The Loss Of Soft Tissues Results In Skeletalisation. At This Stage Of The Body Is Only Hair And Bones.

It May Take Years For A Body To Become Skeletonized When Buried But Weeks In Warm Climates Where The Body Has Been Exposed To Predation.

The Body Has Clearly Reached Its Final Stage Of Decomposition.

:: Note ::

In Water These Stages Still Same With An Additional Stage Which Is Floating Decay Stage, Where The Body Rises To The Water Surface.

At this point, besides aquatic insects such as chironomid larvae and invertebrates such as water snails, terrestrial insect species also colonize the body.


Bodies exposed to action of water or buried in damp, moist soil are opt to undergo certain changes in the course of which they become saponified and the formation of a substance known as adipocere is the result.


If The Body Is In An Environment Which Combines A High Humidity With High Temperatures, The Subcutaneous Body Fat Of The Face, Buttocks (Breasts In The Female) And The Extremities Become Hydrolyzed. Fatty Acids Are Released. These Form Food For Bacteria, Which Can Speed Up The Rate At Which Adipocere Is Made.


Investigating post-mortem interval for a period of at least 3 or more months may mean that there is a large assemblage of flies, beetles and other insects present on the body. These can be use for the calculation of PMI using another method. This method requires that first of all every specimen identified to their family. After that an attempt is made to relate this ‘snapshot’ of decomposition fauna to the succession of insects which routinely colonize a corpse at that site knowing which insects are present and which are absent locally in what season help the entomologist to estimate the PMI.

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