Treatment Log
Definition
The contemporaneous written record of every chemical method applied to an item of evidence, including reagent batch, examiner identity, date/time, and result; required for disclosure under CPIA (UK), BNSS (India), and Federal Rules of Criminal Procedure (US).
- Content
- Chemical method, reagent batch, examiner, date/time, result
- Applies to
- Every chemical method applied to an item of evidence
- UK disclosure basis
- CPIA
- India disclosure basis
- BNSS
- US disclosure basis
- Federal Rules of Criminal Procedure
Common questions
Why is a treatment log required for disclosure rather than just kept for internal quality control?+
Defence counsel is entitled to know exactly what was done to an evidence item, so an incomplete or missing treatment log can be challenged as undermining confidence in the result, independent of whether the underlying chemistry was performed correctly.
What happens if a reagent batch number is missing from the log?+
It becomes harder to rule out a reagent quality or contamination issue as an alternative explanation for a positive or negative result, weakening the evidential value of that particular test.
Related terms
- Alpha-Amino Acids
- Molecules bearing an amine group on the carbon adjacent to the carboxyl group; the primary molecular target of ninhydrin, DFO, and indanedione...
- DFO (1,8-Diazafluoren-9-One)
- A fluorescent ninhydrin analogue used for latent fingerprint development on porous surfaces; excite at 450-470 nm (with secondary absorption extending into the...
- HFE (Hydrofluoroether)
- A class of solvents used as carriers for ninhydrin, DFO, and indanedione formulations; lower toxicity and flammability than older acetone or ethanol...
- Indanedione-Zinc
- A fluorescent amino acid reagent (indane-1,3-dione complexed with zinc chloride) that produces an orange-yellow fluorescent product; reported to be more sensitive than...
- Ninhydrin
- A chemical reagent (2,2-dihydroxyindane-1,3-dione) that reacts with alpha-amino acids in latent print residue to produce a purple-blue compound (Ruhemann's Purple); the primary...
- Physical Developer (PD)
- A multi-bath silver-deposition wet-chemistry method that deposits silver metal onto fatty latent print residue on porous surfaces; the only technique that recovers...
- Ruhemann's Purple
- The purple-blue condensation product formed when ninhydrin reacts with alpha-amino acids; the visible development indicator used in latent fingerprint examination on paper...
- Sequential Processing
- The application of chemical development methods in a fixed, evidence-preserving order that maximises cumulative recovery while preventing earlier treatments from destroying the...
- Vacuum Metal Deposition (VMD)
- A technique in which gold and zinc are sequentially evaporated in a vacuum chamber; the gold deposits uniformly while zinc nucleates differentially...