A forensic examiner examines a single hair recovered from a crime scene and wishes to determine whether it is human or animal, and whether it was shed naturally or forcibly removed. The MOST appropriate technique combining morphology and molecular analysis is:
- A Light microscopy of medullary index and scale pattern, combined with mtDNA extraction from the shaft for species identification and nuclear STR from the root for individual identification ✓
- B Scanning electron microscopy (SEM) of scale pattern alone
- C FTIR spectroscopy of hair keratin to determine species
- D Atomic absorption spectroscopy of trace metals in the hair shaft
Explanation
Forensic hair examination combines macroscopic and microscopic morphology with molecular analysis. Light microscopy assesses medullary index (>0.33 in animals, typically ≤0.33 in humans), scale patterns, pigment distribution, and the presence of a follicular tag (indicating forcible removal). A follicular tag contains nuclear DNA for autosomal STR profiling enabling individual identification. Hair shafts without roots contain mitochondrial DNA (mtDNA) for species identification and maternal lineage but not individual identification. SEM is complementary. FTIR and atomic absorption are not the primary methods for this dual question.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.