ENFSI ENG3-2013
Definition
The ENFSI Glass Expert Working Group guideline for glass comparison casework; specifies the examination sequence, within-source variation requirements, statistical comparison framework, and reporting language for glass fragment comparison in ENFSI member laboratories.
- Minimum comparison parameters
- Density and refractive index
- Full examination sequence
- Visual, refractive index, density, and elemental analysis
- Recommended RI instrument
- GRIM-3
Common questions
What is ENFSI ENG3-2013?+
ENFSI ENG3-2013 is a guideline from the European Network of Forensic Science Institutes that sets the standard for comparing glass evidence. It requires forensic labs to measure at least density and refractive index, and it provides benchmarks so that results from different laboratories can be compared reliably.
How do forensic scientists use this guideline when examining glass?+
The guideline specifies a step-by-step examination sequence: visual inspection first, then refractive index measurement, then density, and finally elemental analysis using techniques like LA-ICP-MS. Each step builds on the previous one to narrow down whether two glass samples could match.
Why does the guideline recommend the GRIM-3 for measuring refractive index?+
The GRIM-3 is listed as the preferred method in the Best Practice Manual because it has strong inter-laboratory proficiency data, meaning different labs using the same equipment get consistent, comparable results. This standardization is important for glass evidence to be reliable in court.
Related terms
- ASTM E1967
- The ASTM International standard for forensic glass RI measurement; specifies three acceptable methods (automated, semi-automated, manual), minimum precision of ±0.0001 RI units,...
- ASTM E2927
- Standard test method for the determination of trace elements in glass samples using LA-ICP-MS; specifies the element suite, calibration standards (NIST SRM...
- GRIM-3
- Glass Refractive Index Measurement, third-generation instrument by Foster + Freeman (UK); an automated phase-contrast hot-stage system that identifies the RI match point...
- LA-ICP-MS
- Laser ablation inductively coupled plasma mass spectrometry; a technique that fires a laser pulse at a sample surface, vaporises a tiny amount,...
- Refractive Index (RI)
- A physical property of glass measuring how much light bends as it passes through. RI is the primary discriminating characteristic used in...
- Within-Source Variation
- The natural variation observed among multiple samples collected from a single source location. Used to estimate the probability of the observed difference...
- ASTM E2365
- The American Society for Testing and Materials standard for forensic comparison of glass by density; specifies temperature control, calibration, and precision requirements...
- Bayesian Likelihood Ratio
- A statistical framework for expressing the evidential value of a comparison: the ratio of the probability of the observed RI similarity given...
- Bayesian Likelihood Ratio (LR)
- The statistical framework that evaluates glass-fragment evidence by comparing the probability of the observed fragment population assuming contact with the source glass...
- Becke Line
- The bright optical halo at the edge of a solid fragment immersed in a liquid, visible under the microscope; moves toward the...
- Bromoform-Bromobenzene System
- The reference liquid mixture used in forensic density-gradient columns and sink-float tests; bromoform (2.890 g/cm³) and bromobenzene (1.495 g/cm³) mix in variable...
- Cauchy Equation
- The empirical equation n(λ) = A + B/λ² + C/λ⁴ that describes the wavelength dependence (dispersion) of a material's refractive index; used...
Explained in these topics
- Density Measurement: Forensic MethodsThe European Network of Forensic Science Institutes guideline for glass evidence comparison; mandates density and refractive index as the minimum comparison pa...
- Glass Comparison: RI, Density and LA-ICP-MSThe ENFSI Glass Expert Working Group guideline for glass comparison casework; specifies the examination sequence, within-source variation requirements, statist...
- Glass: Types, Properties and ManufactureThe ENFSI Glass Expert Working Group guideline for glass comparison casework; specifies the examination sequence (visual, RI, density, elemental), reporting re...
- Refractive Index: Becke Line, GRIM and Mettler Hot StageThe European Network of Forensic Science Institutes Best Practice Manual for Refractive Index Measurement of Glass; the governing European standard, listing th...