Forensic Medicine

1. Blood Stain & Seminal Stains
- Darpan Ghimire
MBBS 3rd year (7th Sem)

2. Every Contact leaves a trace !
- Sherlock Holmes de France

3. Locard’s Exchange Principle:
Wherever he steps, whatever he touches, whatever he leaves, even
unconsciously, will serve as a silent witness against him. Not only his
fingerprints or his footprints, but his hair, the fibres from his clothes,
the glass he breaks, the tool mark he leaves, the paint he scratches, the
blood or semen he deposits or collects. All of these and more, bear
mute witness against him. This is evidence that does not forget. It is not
confused by the excitement of the moment. It is not absent because
human witnesses are. It is factual evidence. Physical evidence cannot be
wrong, it cannot perjure itself, it cannot be wholly absent. Only human
failure to find it, study and understand it, can diminish its value.

4. Blood
• Complex fluid with pH-7.4, cells (45%) & plasma (55%)
• Fresh Blood – Red
Old Blood - Brown
Very Old Blood - Black

5. Collection of blood stains
• Scraped off the surface
• Transferred to a moistened swab
• Cut out of the area bearing stain; carpet swatch

8. Physical Examination:
• Stains found at the crime scene
• Part of body acting as source for blood
• Age of blood stain
• Sex and Age of person
• Antemortem/ Postmortem
• Blood belongs to ?

10. Presumptive Tests
• Catalytic Color Tests
• Test using chemiluminescence & fluorescence
• Spectroscopic Examination
• Microscopic Examination

12. Catalytic Color Tests:
• Benzidine (Adler) Test
• Kastle-Meyer Test
• Kohn or O’kelly Test
• Tetramethylbenzidine
• LMG

13. Test Using Chemi-luminescence
&
Fluorescence

14. Spectroscopic Examination
• Blood is dissolved in water/normal saline and placed in small
test tube which is kept between spectroscope & source of light.
• The solution has property of absorbing some rays from
spectrum, producing characteristic dark absorption bands which
vary with the type of blood pigment present.

15. Microscopic Examination

16. Confirmatory Test ????

17. Crystal Test
• Teichmann or Hemin crystal Test
• Wagenaar Test
• Takayama or Hemochromogen crystal Test

20. Serological Examination
• Immunological Methods
• Isoenzyme Methods

21. Immunological Methods:
• Precipitin Test
• Antiglobulin Consumption Test
• Gel diffusion
• Double Diffusion in Agar cells
• Latex Tests

22. Precipitin Test:
• Principle : When Human serum is brought into contact
with animal serum, antibodies in animal serum react with
proteins in human serum and a visible precipitate is
formed.
• Technique: 2 drops of undiluted antiserum are added
gently to 0.75ml of diluted stain extract.

23. Precipitin Test:

24. Medico-Legal Application

26. Civil Cases:
• Disputed Paternity
• Disputed maternity
• Inheritance Claim
• Divorce and nullity of marriage cases
• Civil negligence

27. Criminal Cases:
• Identification of victims/offenders
• Stains due to bodily fluids
• Crime Scene Reconstruction
• Corroborate/refute an individual’s allegation
• Cases of malingering
• Cause of death
• Time since death

28. Semen
• Consists of 2 compartments; Cellular compartment & Noncellular
compartment.
• In single emission : 2-5 ml; contains about 60-150 million
sperms/ml
• Secretion : alkaline with a pH of 7.4

29. Important terms:
• Aspermia
• Asthenozoospermia
• Azoospermia
• Hyperspermia
• Hypospermia
• Oligospermia
• Necrospermia
• Teratospermia

30. Purpose of seminal Identification

31. Collection of materials
• Clothings
• Vaginal Fluid
• Dried Stains
• Matted Pubic Hair
• Stains on Smooth Surface

32. Sperm Analysis

33. Sperm Analysis
• Preliminary Tests
- Physical Examination
- Chemical Examination
• Confirmatory Tests
- Microscopic Examination

34. Physical Examination
• When fresh, whitish/yellowish-white in color, slightly viscous, jelly-
like, sticky & has characteristic odor.
• Dried seminal stains on clothes: grayish-white/yellowish-gray in
color, shows irregular outline & starchy hard in feeling. When
examined under filtered UV light, they fluoresce with bluish-white
color (due to choline in semen).
• A fresh stain on a non-absorbent material appears translucent.
After a month, it becomes yellow to brown.

35. Chemical Examination
• Florence Test
• Barberio’s Test
• Brentamine fast blue test

36. Florence Test

37. Barberio’s Test

38. Brentamine Fast Blue Test
Most common Presumptive test for seminal acid phosphatase.

39. Confirmatory Test
• Presence of spermatozoa under light microscopy is considered “Gold
Standard”.
• Sometimes, the sample is contaminated by other bodily fluids
(saliva, vaginal secretions), epithelial cells, cellular debris; wherein
selective degradation may be done by treating the cell extract with a
mixture of proteinase K and sodium dodecyl sulfate before staining
and microscopic examination.
• Most commonly used confirmatory test for semen is visualization of
one or more intact spermatozoa after staining with dyes such as
hematoxylin and eosin or ‘Christmas tree’ stain.

40. Microscopic Examination

41. Microscopic Examination

42. Motility of Sperm
• At body temperature, sperms retains full motility in
vagina between 6–12 h, in the uterine cavity for 3–7 days.
Later, the sperms disintegrate into head and tails which
may be recovered from the vagina upto 7–10 days and 12–
14 days in the cervix and uterus.
•„Complete motile sperms may be seen upto 28 h in vagina
after ejaculation (non-motile sperms may be found upto
10 days).
•„Non-motile sperms may be seen in the oral cavity from
2–31 h, in the rectum from 4–113 h, and in the anus from
2–44 h

43. FISH
• Fluorescence in situ hybridization
•This cytogenic analysis uses a Y chromosome specific DNA
probe to identify Y-bearing (male) cells. This technique
identifies not only spermatozoa, but also cells of male
origin and confirms male-female contact.

44. Individualization of sperm
• Blood Group Typing
• Enzyme Typing
• DNA Profiling

45. Blood Group Typing

46. Rules of Inheritance:
• Agglutinogen A or B cannot appear in child unless
present in one or both parents.
• Agglutinogen A1 or A2 cannot appear in child unless
present in one or both parents.
• Combination of A1B parent with A2 child and vice-versa
cannot occur.

47. Rules of Inheritance: (Cont.)
•An O parent cannot have an AB child and an AB parent
cannot have O child.
•Parents of AO and AO genotype may have a OO child.
• Parents of AA or AO genotype may have a A child.

48. References:
• “Review of Forensic Medicine and Toxicology”- Gautam Biswas
• “The Essentials of Forensic Medicine and Toxicology”- Dr. K.S.
Narayan Reddy and Dr. O.P Murty
• Various Research Articles and slideshare

50. Thank You !