Bloodstains and bodily fluids

Plasma

The liquid part of blood

Platelet

Cell fragments that form clots

Serum

Part of plasma that carries protein and electrolytes

Fibrogen

Material that forms clots.

Red blood cells

Cells that transport oxygen.

White blood cells

Cells that fight infections.

Surface tension

The force that pulls surface molecules of liquid together.

Viscosity

Blood is 6 times more viscous than water, meaning it flows 6 times slower.

Specific gravity

The weight of a substance relative to water; blood's specific gravity is slightly higher than water.

Misting pattern

Associated with high-velocity impacts like gunshots or explosions.

Low velocity bloodstain

Bloodstain caused by beating or blunt weapons, 4-6 mm in diameter.

Medium velocity bloodstain

Bloodstain caused by stabbings, 1-3 mm in diameter.

High velocity bloodstain

Bloodstain caused by gunshots, 0.1 mm in diameter.

Angle of impact = 90°

Results in a circular shape of bloodstain.

Angle of impact < 90°

Results in an elliptical shape of bloodstain.

Area of origin

Narrow end of an elliptical bloodstain shows its directionality.

Skeletonized stain

Occurs when the center of a dried bloodstain flakes away, leaving the rim.

Void areas

Areas that appear when something blocks the blood source.

Chemiluminescence

Testing method including luminol and fluorescein for identifying blood.

Kastle-Meyer test

Chemical test reacting with hemoglobin, turning pink if positive.

Seminal fluid

The second most common bodily fluid in forensic cases, containing sperm and seminal acid phosphatase.

Azoospermia

Condition of having no sperm in the ejaculate.

Saliva

Secretion that aids in digestion, containing water, mucus, proteins, salts, and enzymes.

Starch-iodine test

Test used to detect saliva; starch changes color to blue in the presence of iodine.

Urine

Body fluid less frequently tested, detection relies on urea and creatinine.

Clots

• happens after blood leaves the body 

• blood forms a jellylike mass and retracts from the serum