Used to find latent blood

1
Luminol

• Used to find latent blood fluid stains.
• Glows in the dark on contact with blood.
• The Luminol test for blood was developed by
  Walter Specht of Germany in 1937.
• Luminol is sensitive in the parts per million
  range even for blood years old.
• Thus, If you have 1 drop of blood in 999,999
  drops of H2O, Luminol will glow!!

2
Practical Uses at The Scene

• Luminol usually finds use if theres no obvious
  blood evidence in violent or sexual crimes.
• Luminol is mixed fresh.
• Investigators darken the room.
• The room is sprayed with Luminol mixture.
• Areas with blood or fluid evidence glow
  blue-green.
• Glow time is important because different
  materials have different glow durations.

3
Luminol Chemistry

1. Luminol crystals are mixed in water buffered to
   pH 10.5.
2. Hydrogen Peroxide is added the reaction starts.
3. Addition of a catalyst (Iron in blood) speeds up
   the reaction (giving enough light to see!)
4. So youre actually detecting iron catalyst!

Luminol is not radioactive! (in case you wondered)
4
How Luminol Can Help Cold Cases

• Footprints can link a suspect to a crime.
• Trace amounts of blood on a carpet may lead to a
  pool underneath.
• Blood spray patterns can be determined (Useful
  for trajectory and weapon identification).
• Was the body dragged?
• If evidence is found, its videotaped and
  photographed using special techniques.
• Evidence is collected.

5
Drawbacks

• Luminol uses up blood during its reaction and
  thus destroys evidence!
• Other popular crime scene materials like BLEACH
  and Metals react Further blood testing is a
  must!
• The glow of metals fades quickly, but the glow
  of blood lasts longer.
• Experts can tell if they have blood or something
  else.

6
Safety

• Luminol irritates the eyes, skin and lungs.
• Blood can be contaminated with diseases.
• Wear gloves, eye protection and a surgical gown
  to protect against these dangers.
• Decontaminate yourself your gear when youre
  done with dilute bleach.