Quality Assurance, Proficiency Testing, and Error Identification

Why Quality Assurance Matters in a Forensic Lab

Every piece of evidence you process may one day be examined by a defense attorney, a judge, or an accreditation auditor. Quality assurance (QA) is the system of planned, systematic activities that give confidence that a laboratory's work meets defined standards. Without QA, even a skilled technician can produce results that are challenged or excluded in court. The International Association for Identification (IAI) and accrediting bodies such as ANAB (ANSI National Accreditation Board) expect crime scene and forensic labs to maintain documented QA programs aligned with recognized standards.

Core Elements of a Laboratory QA Program

A sound QA program covers four interconnected areas:

Documentation standards. Every action taken on evidence must be recorded at the time it occurs — not reconstructed later. Notes must be contemporaneous (written as you work), legible, dated, timed, and signed. Report language must be objective and free of conclusions that exceed the data. Phrases such as "the suspect touched the object" are opinion, not forensic finding.

Chain of custody (COC). COC is the unbroken, documented record of who collected, handled, transferred, analyzed, and stored each item of evidence. Any gap — a missing signature, an undocumented transfer, or a mislabeled package — creates an exploitable weakness. Courts have excluded otherwise valid evidence solely because COC could not be demonstrated.

Reagent and equipment documentation. Every chemical reagent used must have a lot number, expiration date, preparation date, and preparer's initials recorded in a reagent log. Equipment such as balances, thermometers, and comparison microscopes must have current calibration records. An undocumented or expired reagent raises legitimate questions about whether results are reliable.

Safety documentation. Safety data sheets (SDS) must be accessible for every chemical in the lab. PPE requirements — gloves, eye protection, lab coat, and respirator where vapors are a hazard — must be followed and, in some protocols, documented. Failure to follow safety procedures is not only a QA deficiency; it is a health risk and, depending on jurisdiction, a regulatory violation.

Proficiency Testing

Proficiency testing is a formal evaluation in which a technician processes known or blind samples and is judged against a defined standard. Labs use two types:

• Internal proficiency tests are administered within the lab by a supervisor or QA officer.
• External proficiency tests are administered by an outside provider; the technician does not know in advance whether a sample is a test or a real case (blind external test).

Proficiency tests simulate real casework conditions. You are expected to follow normal procedures, complete all documentation, and reach a defensible conclusion. Results become part of your personnel file and the lab's accreditation record. Failing a proficiency test does not automatically disqualify you, but it triggers a corrective action process — you must show what went wrong and how it will be prevented.

Root-Cause Analysis and Corrective Action

When an error is found — whether in a proficiency test, a case file audit, or an external review — the response is a root-cause analysis (RCA). RCA asks: what was the underlying reason this error occurred, not just what the error was? Common root causes include inadequate training, unclear written procedures (standard operating procedures, or SOPs), time pressure, equipment failure, and poor labeling habits.

A corrective action must address the root cause, not just the symptom. If a technician skipped a COC entry because the log form was confusing, the corrective action is to redesign the form — not simply to remind the technician to be more careful.

Categorizing Errors

During a case file audit you will assign each error to a category:

• Documentation — missing entries, illegible notes, late entries, unsigned forms.
• Procedural — deviation from the written SOP without documented justification.
• Safety — failure to use required PPE, undocumented chemical handling, missing SDS reference.
• Legal — COC gaps, improper evidence release, report language that overstates conclusions.

Legal and COC errors are typically the most damaging to admissibility because they go directly to whether evidence can be authenticated under the rules of evidence.

Safety During This Practicum

Even in a practice setting, treat all biological swab materials as potentially infectious. Follow Standard Precautions: wear nitrile gloves, safety glasses, and a lab coat. Dispose of biological materials in the designated biohazard waste container. Latent-print reagents (such as ninhydrin or cyanoacrylate) may produce irritating vapors; use only in a ventilated area or fume hood, and confirm PPE requirements in the SDS before use. Never pipette by mouth. Wash hands before leaving the lab area.

Connecting QA to Your Credentials

The IAI CCSI and Latent Print certification examinations both test knowledge of QA principles, documentation requirements, and proficiency testing expectations. Your State Evidence Tech Cert may require demonstration of QA-compliant procedures as a condition of licensure. Employers who hire certified technicians expect QA literacy from day one — the habits you build in this practicum are the habits that will protect both the evidence and your career.