Forensic Biology Laboratory Organisation and Accreditation

Laboratory layout separates evidence reception, item examination, clean reagent preparation, extraction, amplification setup and post-amplification work as appropriate to the processes. PCR products contain many copies of selected targets and pose a particular carryover risk. Prevent their movement into areas where unamplified evidence or reagents are handled.

A single universal pressure regime is inappropriate: positive pressure, negative pressure, ventilation and safety cabinets must be assessed for the activity, contamination risks and biological hazards. A biological safety cabinet, a chemical fume hood and a clean PCR workstation do not provide interchangeable protection. Automation can reduce some handling steps while introducing its own carryover and maintenance risks.

Storage follows specimen-specific procedures. Dry stained clothing needs protection from moisture and excessive heat; liquid blood, extracts, tissues and wet items require suitable containers and temperature conditions. Do not freeze every liquid reference specimen by default. Record access, transfers, environmental problems and any changes of packaging.

ISO/IEC 17025:2017 addresses laboratory competence, impartiality and consistent operation. Accreditation assesses specified activities against applicable requirements. Read the actual scope: accreditation for one STR method does not automatically cover mitochondrial sequencing, every substrate or a newly introduced interpretation system.

In the US, ANAB and A2LA are examples of laboratory accreditation bodies; DNA laboratories participating in NDIS must also meet the applicable FBI Quality Assurance Standards. In the UK, UKAS assesses laboratory activities, while the Forensic Science Regulator’s statutory arrangements apply within their specified scope in England and Wales. India’s NABL and Australia’s NATA are further examples. Requirements and recognition arrangements must be checked for the particular activity and jurisdiction.

The 2017 standard is not simply the old two-part list of management and technical clauses. It addresses general, structural, resource, process and management-system requirements. Competence includes suitable staff, equipment, facilities, methods, records and mechanisms for ensuring valid results.

Developmental validation evaluates a method’s underlying capability. Internal validation establishes suitable implementation and limits in the laboratory. Standard methods also require appropriate verification of capability; modified or non-standard methods need validation suited to the change. Neither a vendor brochure nor another laboratory’s accreditation replaces this work.

A quality management system connects approved procedures, training and competence records, equipment checks, reagent tracking, case records, audits and corrective action. Version control matters: the case file must identify which method and interpretation rules were used, including authorised departures and their assessment.

Controls answer particular process questions. An extraction reagent blank follows the relevant extraction steps without an intended specimen. An amplification negative control monitors reaction setup. A positive control checks expected assay performance. A substrate comparison may address background on the item, but it is not interchangeable with a reagent blank.

Unexpected control findings require investigation of the affected work, records and possible causes. Establish which samples or results may be affected and whether reporting should be held. Corrective action can include cleaning, reagent replacement, repeat analysis or resampling where justified. A positive blank does not prove that every sample contains the same contaminant; a clean blank does not prove that no sample-specific contamination occurred.

Proficiency testing and interlaboratory exercises provide further performance information. Tests may be open or blind; participation is not synonymous with blind testing. Use an appropriate provider and the applicable scheme requirements. Internal audits and review of nonconforming work are also needed between external assessments.

The laboratory should ask what an item might answer before consuming it. A bloodstain may support body-fluid testing and DNA analysis; deposition-pattern examination is a different activity requiring appropriate competence. A suspected semen stain may call for sperm microscopy and suitable fluid-marker tests. A DNA profile alone does not identify the fluid it came from.

White blood cells are the principal nuclear-DNA source in ordinary human blood. Semen may contain sperm and other cells, but lack of sperm does not exclude seminal material. Saliva and contact areas can contain cellular and extracellular DNA. Marker specificity, mixtures and contamination affect interpretation.

A hair with adhering tissue may suit conventional nuclear typing; a rootless shaft may retain fragmented nuclear DNA as well as mitochondrial DNA. Bone and teeth require decisions about destructive sampling, preservation and the identification question. No skeletal element always gives the best result, and soft tissue should not be discarded merely because bone is available.

The sampling plan should consider limited quantity, possible mixtures, other examinations and retained material for future review. Record the sampled location and sequence of tests. Coordinate biological work with fingerprint, trace, toxicological, anthropological or dental examinations where the methods could affect one another.

Contamination can arise during collection, manufacture of consumables, transport, examination or analysis. Use appropriate protective clothing, frequent glove changes, item separation, validated cleaning and DNA-controlled consumables. Sterility concerns viable organisms; a sterile product is not necessarily free of amplifiable human DNA.

Keep post-PCR materials away from pre-PCR work. Use dedicated equipment, controlled workflow and checks appropriate to the process. Environmental monitoring and control trends can reveal problems that one batch blank misses. Preventing an incident and detecting it after it occurs are complementary tasks.

Elimination profiles can help investigate unexpected findings associated with staff or other authorised contributors. A candidate association must be assessed under the database procedure, with adequate profile information and relevant case records. It does not by itself prove direct deposition by that person, a laboratory origin or the time of transfer.

Database coverage, consent or other legal basis, access, permitted uses, retention and investigation procedures require governance. Do not assume that every person who ever entered a facility has a stored profile. Record the assessment and any effect on the case, including findings that remain unexplained.

A report identifies the items examined, relevant condition, sampling, methods, findings, interpretation and limitations. Donor-related statistics need stated propositions and assumptions. A random match probability is not the probability that the named person is innocent; a likelihood ratio compares the probability of findings under specified propositions.

Technical review checks whether the data, methods and conclusions are supported. Administrative review checks the report and required records. Their allocation follows the applicable quality system. The reviewer needs access to the material necessary to assess the work; a name on a report is not a substitute for recorded review.

In US federal proceedings, Rule 702 governs expert testimony, informed by Daubert and later decisions. Testability, peer review, error considerations and acceptance are relevant factors, not a rigid checklist that every method must satisfy identically. State rules vary. A doctoral degree is not a universal legal prerequisite, and method reliability does not remove the need to assess the expert’s qualifications and application.

In England and Wales, the Forensic Science Regulator Act 2021 underpins the statutory code; it is not a supposed “Forensic Science Regulator and Biometric Strategy Act 2023.” Expert duties and reporting also depend on procedural rules. India’s Bharatiya Sakshya Adhiniyam, 2023 contains provisions on expert opinion, with applicability depending on the proceedings. Other jurisdictions have their own requirements. Accreditation supports assessment of competence but does not replace the court’s admissibility decision.