1. Forensics Serology

2. Forensic Serology
Analysis and screening of body fluids Usually hand-in-hand with DNA analysis

3. Common Cases
Most involve sexual assaults (sexual assault kits, complainant clothing, bedding, suspect clothing) Others: homicides, aggravated assault, burglaries (blood from crime scene, clothing, weapons, etc)

4. Collecting Specimens
If its small enough, its simply brought to the lab
Otherwise, collected on a cotton swab or part of the evidence with bodily fluid is cut off from the item for submission

5. Bodily Fluids
Blood
Semen
Saliva
Sweat
Feces
Urine

6. Excreted vs. Secreted Excretion is the removal of material
Sweat, breast milk, earwax, feces, chyme, bile, vomit, aqueous humour (watery substance that covers the eye), sebum (skin oil), urine
Secretion is movement of material from one point to another
Blood/plasma, semen, saliva, serum

7. Testing
Definitive – The sample is definitely the specific target and cannot possibly be something else
Presumptive
The sample is definitely not a certain substance
The sample is probably the substance

8. Saliva Tests Reveal Disease markers (HIV, cancer) Viral infections
Presence of therapeutic & illicit drugs (only hours) (THC, heroine, cocaine, amphetamines)

9. Saliva
99.5% - water
0.5% - electrolytes, mucus, glycoproteins, enzymes, and antibacterial compounds
Humans produce 1.0 – 1.5 L a day!
Alpha-amylase – breaks down complex carbohydrates into smaller sugar molecules (breaks down starch)
B-amylase: Plant & bacterial sources
A-amylase: HSA (human saliva), HPA (human pancreas)

10. Alpha-Amylase Overlay– Presumptive Assay
Qualitative only (positive or negative)
Spray a Whatman paper circle with solution of soluble starch
Lay the paper down over the suspected saliva stain
Leave in contact with stain for 20 minutes
Incubate in a 37 deg moisture chamber for 1 hour, then dry
Spray with iodine and look for a lack of color change to deep blue-black

12. Phadebas Method – Presumptive
Tablets consist of insoluble starch polymers to which a blue dye has been covalently bound
Add putative saliva stain to water
Add tablet
When amylase is present:
Polymers are degraded
Dye is liberated and becomes soluble
Concentration of soluble dye is measured by spectrophotometry at 620 nm

13. Direct, Less Presumptive Test
Lateral Flow Immunochromatographic Strip Test or Rapid Stain Identification (RSID) Saliva kits
Detects for the a-amylase molecule itself, specifically the one in human saliva
Can test various surfaces such as those on paper, cigarette butts, plastic or glass bottles, metal cans, etc.
Tricky….. Why?

14. Feces / Urine Not as common
Swabbed, bagged, placed in vials to be air-tight and prevent cross-contamination

15. Factors that Effect Urine
Amount produced – liquid intake, temperature, physical activity
What effects different components found in urine? Health and diet

16. What’s in Urine Urochrome pigment (what makes the yellow color)
Crystalline substances
Epithelial cells from the urinary tract lining

17. Urea
Second largest constituent of urine & the product of the breakdown of protein
Body puts of ~30g a day
Crystals form when combined with xanthydrol and acetic acid
Urea will also turn pink/red in the presence of p-dimethylaminocinnamaldehyde (DMAC)

18. Can you find DNA in urine?
Sometimes….. But it’s poor
There’s no DNA in actual urine
However, since it is stored in the bladder and goes through the urethra, you can sometimes get the lining epithelial cells
Better with a liquid sample properly stored
Who has more DNA-containing cellular material in their urine – male or female?

19. Urine Test Finding it – color, smell, chemical mapping Presumptive
Smell? Ammonia (from the break down of urea)
Methods? Microcrystalline tests, color tests, TLC (thin layer chromatography), GC/MS, radial gel diffusion, immunoassays

20. Presumptive Assay
Prepare Whatman filter paper circle with one drop of bromothymol blue, a pH indicator dye
Yellow-green at pH 6
Aqua blue at pH greater than 7.6
Allow bromothymol blue to dry
Add drop of extract from evidence sample on top of dye, then add drop of urease
If urea present, urease will degrade to ammonia
Ammonia will raise pH and dye will turn aqua blue

22. Immunological Assay RSID-urine
Tests Tamm Horsefall glycoprotein (abundant in urine)
Not specific for human urine

23. Feces Brown color due to bilirubin
Smell? Break down of amino acids into skatole, indole, and methyl-mercaptan by bacteria
Made of dead bacteria (that aids in digestion), living bacteria, protein, undigested food residue (fiber), waste material from food, cellular linings, fat, salts, mucus from intestines and the liver

24. Feces Detection – Confirmation Assay
Compound microscope (extract it in water, stain using KPIC, and mount on a slide)
Look for animal and plant cells (digestion)

25. Presumptive Assay Prepare extract of feces stain
Oxidize urobilinogen (a breakdown compound from bilirubin) to urobilin
Add zinc chloride
If urobilin present, extract will fluoresce under UV light
Glows green!
Used in cases of “gassing” in prisons