DeHaan Modification
Definition
A refinement of the Griess test procedure for forensic propellant residue detection, using a combined sulphanilic acid + NEDA reagent on filter paper for the contact transfer. Attributed to John DeHaan and widely referenced in US forensic firearms literature.
- Base method
- Griess test for propellant residue
- Reagent
- Sulphanilic acid plus NEDA on filter paper
- Attributed to
- John DeHaan
Common questions
What problem does the DeHaan modification address in the Griess test?+
It provides a combined single-reagent contact-transfer method on filter paper, simplifying the classic two-step Griess procedure for lifting nitrite residue patterns around a bullet entrance.
What does the resulting colour reaction indicate at a shooting scene?+
A pink to reddish colour on the treated filter paper marks nitrite deposits from unburned or partially burned propellant, helping estimate firing distance from the residue pattern's size and density.
Related terms
- Azo Dye
- A class of organic dyes containing one or more azo groups (R-N=N-R'). Formed in the Griess test by coupling of a diazonium...
- BSA 2023 (Bharatiya Sakshya Adhiniyam)
- India's evidence statute enacted in 2023, replacing the Indian Evidence Act 1872. Sections 39-46 govern expert testimony, including the admissibility and presentation...
- Contact Wound
- A firearm wound produced when the muzzle is pressed against or within a few centimetres of the target surface. Characterised by a...
- Modified Griess Test
- A contact-transfer colour chemistry test for nitrite-containing propellant combustion residue. Sulphanilic acid undergoes diazotisation with nitrous acid (from NO2 on the target...
- NEDA (N-(1-Naphthyl)ethylenediamine Dihydrochloride)
- The azo coupling component in the modified Griess test. After diazotisation of sulphanilic acid with nitrous acid, NEDA couples with the diazonium...
- NIJ Range Estimation Guidelines
- NIJ Standard 0612.00 (US National Institute of Justice). The primary US guidance document for firing-distance determination methodology, covering test-fire protocols, pattern comparison...
- Sodium Rhodizonate
- A chelating agent producing a scarlet-to-red colour with lead ions at acid pH. Applied to entry-wound margins and garment entry holes to...
- Stippling (Tattooing)
- Discrete punctate abrasions or haemorrhages around an entry wound from individual unburned propellant granules embedding in the epidermis at intermediate range. Unlike...
- Test-Fire Envelope
- The set of reference targets produced by firing the case weapon (or a ballistically equivalent substitute) loaded with the same ammunition at...