Lecture 9 - Blood spatter analysis Flashcards
What are the cohesive properties of blood?
The formation of blood droplets in flights
What are the adhesive properties of blood?
The formation of bloodstains
What type of blood cells has no nucleus or DNA?
Red blood cell
What type of blood cell is targeted for screening test?
Red blood cell due to the presence of the haem molecule
What type of blood cell is targeted for DNA analysis?
White blood cells due to the presence of a nucleus and DNA
What is involved in the Hemastix presumptive blood test?
Test strip containing TMB is rubbed against suspected stain with a drop of sterile water. Positive results gives a green colour reaction
What is involved in the Kastle Meyer presumptive blood test?
Swab with phenolphthalein is rubbed against suspected stain with ethyl alcohol and hydrogen peroxide. Positive results gives a pink colour reaction as haem reacts.
What is involved in the immunochromatographic assay confirmation blood test?
Employs an antibody-antigen-antibody sandwhich method using antibodies that recognise human hemoglobin
What blood enhancer produces a chemiluminescent product?
Luminol
What blood enhancer produces a fluorescent product?
Hemascein
What blood enhancer produces a dark blue or black product?
Amido black
What blood enhancer produces a blue/green product?
Leuco malachite green
What are the steps of blood droplet formation?
Sheet - lattice - ligaments - beading - droplets
Passive bloodstain
Formed with gravity acting as the main force produces drip and flow patterns and pooling of blood.
Spatter bloodstain
Formed with an additional force acting on the blood source. Droplets are propelled through the air, dispersing into smaller drops
Transfer bloodstain
Formed from contact between a blood-bearing surface and another. Either through compression or lateral movement of the surfaces
Altered bloodstain
Formed with characteristics indicating a physical or physiological changes
Cast off bloodstain
Resulting from blood being projected in motion
Arterial bloodstain
Resulting from blood spurting from wound
Fly blood spots
Resulting from fly activity transferring blood
Void bloodstain
Resulting from a secondary object coming between blood spatter and final target
What is used to measure a bloodstain?
Microscopic lense with scale
What bloodstain feature is determined through 2D representation?
Area of convergence
What bloodstain feature is determined through 3D representation?
Region of origin
What do the letters of blood types indicate?
Antigens on the surface of red blood cells and the corresponding antibodies in the plasma
