Presumptive Testing

Question 1

What do presumptive blood tests rely on?

Answer 1

Reaction between different substances/chemicals to change colour when in contact with blood.

Question 2

What do presumptive blood tests require?

Answer 2

Confirmation testing and further lab analysis of sample

Question 3

Give some examples of presumptive blood tests.

Answer 3

Hemistix
Hemident (McPhail’s Reagent)
Hexigon OBTi

Question 4

How is Hexigon OBTi different from other presumptive blood tests?

Answer 4

Differentiates between human and animal blood

Question 5

What are the benefits of presumptive blood tests?

Answer 5

Small, disposable, non-destructive, easy to use in the field

Question 6

What are blood enhancers/locaters?

Answer 6

Can be used after presumptive tests have confirmed stain is blood or to locate staining that may not be visible?

Question 7

How does blood appear under ALS?

Answer 7

DOES NOT fluoresce. Appears darker

Question 8

Give examples of blood enchancers/locaters (4)

Answer 8

Luminol or blue star
Hungarian Red
Amido Black
Leuco Crystal Violet

Question 9

When would you use Luminol or Blue Star?

Answer 9

Cleanup scene

Question 10

How do blood enhancers/locaters work?

Answer 10

These materials have high affinity to heme compounds found in blood and not the typical composition of eccrine/sebaceous substituents found in fingerprints.

Question 11

To what dilution can Luminol or Blue Star identify blood?

Answer 11

1:10,000

Question 12

What are some cons of Luminol/Blue Star?

Answer 12

Dissipates, difficult to capture, needs to be dark
Subject to false positives (may react with household products)

Question 13

Does Luminol/Blue Star allow for DNA analysis?

Answer 13

Yes

Question 14

What is Hungarian Red?

Answer 14

Dye used to enhance (NOT locate) bloody footwear or fingerprint impressions

Question 15

What type of backgrounds/surfaces can Hungarian Red be used on?

Answer 15

Busy backgrounds
Most porous and non-porous surfaces

Question 16

Can DNA analysis be conducted after use of Hungarian Red?

Answer 16

No

Question 17

What is Amido Black?

Answer 17

Protein stain that turns impressions a dark blue colour

Question 18

What are pros of Amido Black?

Answer 18

Very sensitive
Works well on both porous and non-porous items

Question 19

What is LCV?

Answer 19

Enhancer that produces a blue to purple/volet colour during reaction

Question 20

What are the pros of LCV?

Answer 20

High affinity to heme-based materials
May be used on porous and non-porous materials