Unit 4: Biological Evidences
4.1 Types of Biological Evidences: Blood, Semen, Saliva and Other Body Fluids
The crime’s biological traces: blood (the violence’s marker — the stains, the spatter, the drops); semen (the sexual offences’ core — the stains, the swabs); saliva (the bites, the cigarette ends, the stamps — the amylase’s detection); urine-and-faeces (the scene’s presence); vaginal-and-anal secretions (the swabs of the sexual offences); hair-with-roots (U6’s trace-but-biological bridge); tissue-and-bone (the body’s fragments); vomit (the poisoning’s faces). The evidence’s forms: the liquid, the stains, the dried, the mixed.
4.2 Importance of Biological Evidences
- The identification — the source’s determination (the person’s-and-body’s linking).
- The scene’s reconstruction — the event’s biology (the spatter’s pattern — the struggle’s story; the stains’ distribution).
- The offence’s proof — the sexual offence’s corpus (the semen-and-DNA); the violence’s confirmation.
- The exclusion — the innocent’s elimination (the foreign sample’s exclusionary power).
- The paternity-and-kinship — the civil faces (the succession-and-status disputes — U4.4-and-U5.5’s line).
4.3 Scientific Examination of Biological Evidences
The presumptive tests (the screening): the blood’s — the Kastle-Meyer (the phenolphthalein’s pink), the luminol (the invisible stains’ glow — the cleaned scenes’ revelation); the semen’s — the acid phosphatase; the saliva’s — the amylase. The confirmatory tests: the blood’s — the Teichmann-and-Takayama crystals (the haemoglobin’s proof); the human-origin’s tests (the precipitin — the species’ determination); the semen’s — the microscopy (the spermatozoa) and the prostate-specific antigen. The individualisation: the blood’s grouping (U4.4) and the DNA’s profiling (U5) — the source’s narrowing-to-identification. The documentation: the stains’ photography-and-sketching; the sampling (the cutting, the swabbing, the standard samples’ collection).
4.4 Significance of ABO Blood Types in Paternity and Crime Investigation
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