DFSL MaharashtraGovernment of Maharashtra

Methodologies

Standard procedures and what has changed at the bench

The standard operating procedure in force for each division is set out below, followed by the evolution of methods. Older reports remain valid records of what was done at the time; the timelines show what the laboratory would add today.

Standard operating procedures in force

8 procedures circulated to the divisions. Each states the examination sequence, the control checks that must accompany it and what has to appear on the face of the report.

SOP/DNA/04Autosomal STR profiling of biological exhibits
Rev 4.1 · effective April 2022

Applies to swabs, stains on cloth, tissue, blood in EDTA, bone and reference buccal swabs forwarded for individualisation or kinship comparison.

Supersedes SOP/DNA/03 (PowerPlex 21 workflow, 2016).

Examination sequence

  1. 1. Receipt Verify parcel count against the forwarding letter, photograph seals, and record any deviation before opening.
  2. 2. Screening Screen the stain with presumptive chemistry or a card test and map the sampled area on the exhibit sketch.
  3. 3. Extraction Automated silica column extraction; organic extraction with demineralisation for bone and calcified tissue.
  4. 4. Quantification Real-Time PCR quantification with degradation index; select input volume from the quantification value, not by default.
  5. 5. Amplification Expanded STR kit of the GlobalFiler class with positive control, negative control and reagent blank in every batch.
  6. 6. Interpretation Apply the analytical and stochastic thresholds on record; interpret mixtures against the deconvolution worksheet before any comparison.

Quality control

  • Reagent blank and negative control in every extraction batch
  • Allelic ladder run with each capillary injection set
  • Second qualified examiner verifies every reported profile and exclusion

Reporting requirement

State the kit and loci examined, number of loci reported, and a random match probability or kinship statement. Partial profiles must carry an explicit statement of discriminatory power.

References

NABL 112 requirementsSWGDAM interpretation guidelinesSection 45, Indian Evidence Act

Applies to: DNA, Biology + DNA, Wildlife DNA

SOP/TOX/07Screening and confirmation of poisons in viscera and body fluids
Rev 7.0 · effective January 2021

Viscera, blood, urine, gastric lavage and suspected residue in poisoning, custodial death and unnatural death references.

Supersedes SOP/TOX/06 (screening by colour tests and TLC alone).

Examination sequence

  1. 1. Receipt Record preservative used, condition of jars and any leakage. Reject unsealed material with a written intimation.
  2. 2. Preliminary Colour and spot tests recorded as screening only, never as an identification.
  3. 3. Extraction Acid, basic and neutral extraction as applicable; separate aliquot retained for confirmation.
  4. 4. Confirmation GC-MS or LC-MS/MS against a certified reference standard run in the same batch.
  5. 5. Quantification Calibration curve of not fewer than five points with a quality control sample at two levels.
  6. 6. Retention Retain remnants under seal for the period prescribed so a re-examination remains possible.

Quality control

  • Certified reference standard in every confirmation batch
  • Solvent blank between samples to exclude carryover
  • Calibration verification recorded in the instrument log before analysis

Reporting requirement

Report the compound identified, the confirmatory technique used and the quantitative figure with units where the matrix allows. Screening-only findings must be stated as such.

References

NABL 112 chemical testing clausesSection 293, Indian Evidence ActCrPC 174 requirements

Applies to: Toxicology

SOP/BAL/03Firearm linkage, test firing and discharge residue
Rev 3.2 · effective August 2020

Seized firearms, fired cartridge cases, bullets, wads, clothing of the deceased and residue swabs from the hands or garments.

Examination sequence

  1. 1. Condition Examine and photograph the firearm as received, record serviceability and trigger pull before any firing.
  2. 2. Test firing Test fire in the laboratory range with ammunition of the same calibre; retain test fired specimens under exhibit numbers.
  3. 3. Comparison Compare breech face, firing pin and chamber marks under the comparison microscope; capture photomicrographs of agreeing detail.
  4. 4. Residue Modified Griess test for nitrite as a screen, followed by SEM-EDX for lead, barium and antimony particles.
  5. 5. Range Opine on range only where the residue pattern and the control target series support it.

Quality control

  • Control target series fired at measured distances for every range opinion
  • Photomicrographs of the agreeing detail stored with the case file
  • Peer verification of every conclusive linkage

Reporting requirement

Record class and individual characteristics separately. Where deformation limits the comparison, the opinion must be qualified rather than stated as conclusive.

References

Arms Act 1959 examination requirementsAFTE range of conclusionsSection 45, Indian Evidence Act

Applies to: Ballistics, Physics

SOP/CYB/05Acquisition and examination of digital exhibits
Rev 5.3 · effective March 2023

Mobile handsets, storage media, computers, DVRs and cloud account data forwarded with authority.

Supersedes SOP/CYB/04 (logical extraction workflow, 2018).

Examination sequence

  1. 1. Isolation Keep the device shielded or in flight mode; photograph the device, IMEI and seal condition on receipt.
  2. 2. Hashing Compute SHA-256 of the acquired image before examination and again on completion; record both in the case file.
  3. 3. Acquisition Prefer full file system or physical acquisition; record the tool name and version used for the extraction.
  4. 4. Examination Work only on the verified working copy; parse applications, deleted records and timeline artefacts.
  5. 5. Certification Issue the Section 65B certificate with the report, naming the person in lawful control of the device.

Quality control

  • Write blocker used for all mass storage acquisition
  • Tool version and licence state recorded per case
  • Hash comparison before and after examination retained on file

Reporting requirement

State extraction type, tool and version, hash values, and clearly separate recovered content from interpretation.

References

Section 65B, Indian Evidence ActSection 63, Bharatiya Sakshya AdhiniyamIT Act 79A accreditation requirements

Applies to: Cyber Forensic

SOP/NDPS/02Identification and purity determination of narcotic substances
Rev 2.4 · effective June 2022

Material seized under the NDPS Act, including samples drawn before a Magistrate under Section 52A.

Examination sequence

  1. 1. Inventory Verify the Section 52A inventory and the seal impression against the specimen seal before opening.
  2. 2. Weight Record gross and net weight on a calibrated balance, with the weight of packing noted separately.
  3. 3. Screening Microscopic examination and appropriate colour tests as a screen only.
  4. 4. Identification GC-MS or FTIR identification against a reference standard.
  5. 5. Purity HPLC quantification where the quantity classification in the charge depends on purity.

Quality control

  • Balance calibration verified on the day of weighing
  • Reference standard chromatogram appended to the analytical schedule
  • Remnant resealed with the laboratory seal and returned with the report

Reporting requirement

Report net weight, the substance identified, purity where determined, and the resulting quantity classification only as an arithmetical statement.

References

NDPS Act Sections 21, 52AStanding Order 1/88 samplingSection 293, Indian Evidence Act

Applies to: Narcotics

SOP/QD/06Comparison of handwriting and signatures
Rev 6.0 · effective November 2021

Questioned signatures and writings with admitted, specimen or contemporaneous comparison material.

Examination sequence

  1. 1. Sufficiency Assess whether the admitted material is contemporaneous and sufficient in quantity before beginning the comparison.
  2. 2. Examination Stereomicroscopic examination of line quality, pen pressure, pen lifts and hesitation.
  3. 3. Instrumentation Video spectral comparator for ink differentiation, erasures, additions and indented writing.
  4. 4. Comparison Record agreements and differences separately; note natural variation range of the writer.

Quality control

  • Photographic charts of the compared characteristics retained with the file
  • Second examiner review before any opinion of common authorship
  • Photocopy material examined only with a recorded limitation

Reporting requirement

State the material examined, the limitation arising from photocopies or insufficient specimens, and the opinion on the recognised scale.

References

Section 45 and Section 73, Indian Evidence ActASTM E2290 practice

Applies to: Questioned Documents

SOP/EXP/02Examination of post-blast debris and explosive residue
Rev 2.1 · effective February 2020

Debris, swabs, soil and control samples from explosion sites, and recovered bulk explosive or detonators.

Examination sequence

  1. 1. Segregation Open debris parcels separately from residue swabs in different cabinets to exclude cross contamination.
  2. 2. Screening Spot tests for nitrate, nitrite and chlorate; thin layer chromatography for organic explosives.
  3. 3. Confirmation FTIR for bulk material, ion chromatography for inorganic anions and GC-MS for organic residues.
  4. 4. Control Analyse the control soil or surface sample in parallel and report the comparison.

Quality control

  • Control sample analysed in the same batch as the questioned residue
  • Blank swab from the same lot analysed to exclude contamination
  • Delay between incident and collection recorded as a limitation

Reporting requirement

Identify the formulation class where the residue permits, and record contamination or delay as a limitation on the face of the report.

References

Explosive Substances Act 1908Section 45, Indian Evidence Act

Applies to: Explosives

SOP/BIO/03Serological screening of scene and body exhibits
Rev 3.0 · effective July 2019

Clothing, bedding, weapons, swabs and scene lifts examined for blood, semen and saliva.

Supersedes SOP/BIO/02 (Benzidine screening, withdrawn on health grounds).

Examination sequence

  1. 1. Drying Air dry damp exhibits in a controlled cabinet before examination and record the condition on receipt.
  2. 2. Mapping Map and number every stain examined so the DNA sampling point can be traced back.
  3. 3. Screening Phenolphthalein for blood, microscopy for spermatozoa, card tests for human origin.
  4. 4. Referral Refer positive stains for STR profiling on the same mapped area.

Quality control

  • Positive and negative controls with every card test lot
  • Separate instruments per exhibit to prevent transfer
  • Condition of damp or mouldy exhibits recorded before examination

Reporting requirement

Report screening results as presumptive unless a confirmatory test was applied, and state the species finding separately from individualisation.

References

NABL 112 biology clausesSection 45, Indian Evidence Act

Applies to: Biology & Serology, Biology + DNA

DNA profiling

Maharashtra laboratories moved from blood grouping and early multiplex kits to expanded STR panels with automated extraction and quantification.

  1. Up to 2010Blood grouping and early RFLP work
    Superseded

    Association was mostly at class level through ABO grouping and absorption-elution. Individualisation was rarely possible and casework often stopped at species and group.

  2. 2010 to 2016AmpFlSTR Identifiler and Identifiler Plus
    Superseded

    Fifteen autosomal loci plus Amelogenin on ABI 3130xl platforms. Adequate for clean reference comparisons but thin on degraded or mixed material.

  3. 2016 to 2021PowerPlex 21 and mini-STR supplements
    Still accepted

    Twenty autosomal loci with better tolerance for inhibition. Mini-STR markers were added for degraded bone and tissue.

  4. 2021 onwardsExpanded kits, automation and probabilistic mixture work
    Current practice

    GlobalFiler class kits with 24 markers, automated extraction, Real-Time PCR quantification with degradation indices, and structured mixture interpretation. Current laboratory practice for fresh and challenged samples.

Toxicology

Screening has shifted from colour tests and TLC alone to instrument confirmation with quantification, which matters for weight in court.

  1. Up to 2012Colour tests and thin layer chromatography
    Superseded

    Useful for screening but not sufficient on their own for a confirmed identification of a specific compound.

  2. 2012 to 2018GC and GC-MS confirmation
    Still accepted

    Gas chromatography with mass spectrometry became the confirmation standard for pesticides, alkaloids and volatiles.

  3. 2018 onwardsLC-MS/MS with quantification
    Current practice

    Liquid chromatography tandem mass spectrometry with calibrated quantification, plus AAS for heavy metals. Quantitative values are now expected wherever the matrix allows.

Ballistics and firearm discharge residue

Comparison microscopy remains the backbone, now supported by instrumental residue analysis and image documentation.

  1. Up to 2014Comparison microscopy with chemical residue tests
    Still accepted

    Firing pin, breech face and striation comparison with Walker's test or modified Griess test for nitrite. Documentation was largely descriptive.

  2. 2014 to 2020Digital imaging and SEM-EDX for residue
    Still accepted

    Photomicrograph documentation of matching striations along with scanning electron microscopy and energy dispersive X-ray for particle level residue.

  3. 2020 onwardsInstrumented residue analysis with documented comparison sets
    Current practice

    SEM-EDX for characteristic lead, barium and antimony particles, ICP-MS where trace levels matter, and stored digital comparison images that can be re-examined.

Digital and cyber forensics

Tooling changes fast. The extraction method and tool version decide what can be recovered, so both belong in every report.

  1. Up to 2015Manual examination and early imaging tools
    Superseded

    Photographs of screens, logical copies and limited deleted data recovery. Hashing was inconsistent across cases.

  2. 2015 to 2021Cellebrite UFED and Magnet AXIOM workflows
    Still accepted

    Physical and file system extraction with hash values recorded before and after examination, plus structured application parsing.

  3. 2021 onwardsCurrent suite with cloud and encrypted app support
    Current practice

    Later Cellebrite and AXIOM releases with full file system and keychain acquisition, cloud token handling, and Section 65B compliant certificates generated alongside the extraction.

Serology and biology

Serology is now a screening step that feeds DNA work rather than a stand-alone conclusion.

  1. Up to 2012Benzidine, Takayama and ABO grouping
    Superseded

    Benzidine was later withdrawn from routine use on health grounds. Grouping gave class level association only.

  2. 2012 to 2018Phenolphthalein screening with precipitin species tests
    Still accepted

    Safer presumptive chemistry with anti-human precipitin for species origin, followed by referral for DNA where individualisation was needed.

  3. 2018 onwardsRapid immunochromatographic screening feeding STR profiling
    Current practice

    Card based tests for blood, semen and saliva, followed by STR profiling on the same stain so the conclusion reaches individual level.

Method status at a glance

  • AmpFlSTR Identifiler Plus
    Superseded

    Standard until roughly 2016. Current practice: Expanded STR kits of the GlobalFiler class with automated extraction and Real-Time PCR quantification..

  • PowerPlex 21 System
    Still accepted

    Standard until roughly 2021. Current practice: Expanded 24 marker kits with degradation indices, retained for casework continuity where the earlier profile must be compared directly..

  • ABO grouping by absorption-elution
    Superseded

    Standard until roughly 2012. Current practice: Presumptive screening followed by STR profiling of the same stain for individual level association..

  • Benzidine test
    Superseded

    Standard until roughly 2012. Current practice: Phenolphthalein or card based immunochromatographic screening..

  • Takayama test
    Still accepted

    Standard until roughly 2015. Current practice: Confirmatory immunological tests with DNA referral for the same stain..

  • Colour tests and thin layer chromatography alone
    Superseded

    Standard until roughly 2012. Current practice: Screening followed by GC-MS or LC-MS/MS confirmation with quantification wherever the matrix allows..

  • Walker's test / modified Griess test
    Still accepted

    Standard until roughly 2018 as a stand-alone residue finding. Current practice: SEM-EDX for characteristic lead, barium and antimony particles, supported by the chemical test as a screen..

  • Cellebrite UFED 4PC
    Still accepted

    Standard until roughly 2021 for encrypted application data. Current practice: Current Cellebrite and Magnet releases with full file system acquisition, cloud token handling and a Section 65B certificate issued with the extraction..

  • Immunoassay screening without confirmation
    Superseded

    Standard until roughly 2015. Current practice: Immunoassay used only as a screen, with LC-MS/MS confirmation before reporting..