Direct Comparison
Definition
Side-by-side physical and spectroscopic comparison of the questioned chip with a sample from the suspect vehicle; the mandatory final stage in any automotive paint comparison.
- Compares
- Questioned paint chip against suspect-vehicle sample
- Methods
- Physical layer matching and spectroscopy
- Stage
- Mandatory final step of a paint comparison
- Field
- Automotive paint trace evidence
Common questions
Why is direct comparison always the final step rather than the first?+
Database searches (such as PDQ or EUCAP) narrow candidate makes, models, and paint formulations first, and direct physical and spectroscopic comparison against an actual suspect-vehicle sample then confirms or excludes the specific match those searches suggested.
What can prevent a direct comparison from reaching a conclusive result?+
A small or degraded questioned chip may lack enough layer structure or sample volume for full spectroscopic analysis, and repainted or repaired vehicle panels can introduce layer sequences that no longer match the vehicle's original factory finish.
Related terms
- BKA (Bundeskriminalamt)
- German Federal Criminal Police Office; custodian of EUCAP and primary German forensic laboratory for automotive paint comparison.
- BNS 2023 § 106
- Bharatiya Nyaya Sanhita 2023 provision criminalising causing death by negligence; the primary charging provision for fatal hit-and-run cases in India, with enhanced...
- ENFSI EPG
- Expert Working Group on Paint (European Network of Forensic Science Institutes); produced the European paint-examination protocol and promoted EUCAP development.
- ENFSI FIRM
- Forensic Intelligence and Reporting Model; verbal LR scale from 'inconclusive' through 'limited', 'moderate', 'strong', and 'very strong' support used in European trace-evidence...
- EUCAP
- European Collection of Automotive Paints, maintained at the Bundeskriminalamt (BKA) in Wiesbaden; the European counterpart to PDQ for automotive hit-and-run paint comparison.
- FSR Codes of Practice
- The Forensic Science Regulator's Codes of Practice and Conduct, made statutory by the Forensic Science Regulator Act 2021, setting mandatory quality standards...
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- PDQ (Paint Data Query)
- RCMP-maintained international automotive paint database. Stores binder, pigment and layer data for vehicle original-equipment finishes from major manufacturers. Used to narrow a...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...
- Spectral Cross-Correlation
- A mathematical similarity measure comparing two FTIR spectra; PDQ uses cross-correlation scores to rank candidate matches; a score above 0.90 is treated...
- SWGMAT
- Scientific Working Group for Materials Analysis, a US forensic science standards body (now succeeded by the OSAC Explosives Subcommittee). Published the Forensic...