Tag Archives: chain-of-custody

Sample Labeling and Sealing Functions for Field Collection

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Sample labeling and sealing functions are critical for ensuring the integrity and traceability of biological evidence during field collection. These functions include clearly marked labels and tamper-evident seals, providing crucial documentation for chain of custody. The labeling ensures proper identification, while the sealing prevents contamination and unauthorized access. These features are particularly important in forensic investigations, cold-case analysis, and clinical research, ensuring reliable DNA recovery and maintaining the integrity of the samples for analysis.

Key Features:

  • Clear, durable labels for sample identification

  • Tamper-evident seals to prevent contamination

  • Ensures proper chain of custody

  • Ideal for forensic and clinical sample collection

Application Scope:

  • Forensic evidence handling and crime scene investigations

  • Cold-case analysis and DNA preservation

  • Clinical diagnostics and research

  • Legal and criminal justice applications

Standardized Collection for Forensic Casework

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Standardized collection in forensic casework is a rigorous, protocol-driven process designed to ensure the integrity, admissibility, and reliability of physical evidence gathered from crime scenes, victims, or suspects. It eliminates variability in evidence handling, minimizes contamination risks, and aligns with legal and scientific standards—critical for supporting investigations and securing justice in court. Unlike ad hoc collection methods, standardized protocols outline step-by-step procedures for evidence identification, documentation, collection, preservation, and chain-of-custody tracking, ensuring that every piece of evidence is treated with the precision required to withstand scientific scrutiny and legal challenges.

Core Principles & Step-by-Step Protocol

Forensic casework collection adheres to four foundational principles: minimize contamination, document comprehensively, preserve evidence integrity, and maintain chain of custody. The standardized workflow includes:
  1. Preliminary Assessment & Scene Securing: First responders secure the crime scene to prevent unauthorized access. Forensic investigators conduct a walkthrough to identify potential evidence (e.g., DNA, fingerprints, weapons, trace materials) and prioritize collection based on fragility (e.g., biological evidence before environmental exposure).
  2. Documentation: Each piece of evidence is photographed (with scales for size reference), sketched, and documented in a crime scene log. Details include location, time of collection, collector’s name, and condition of the evidence. Digital documentation uses metadata to ensure authenticity.
  3. Contamination Control: Investigators wear personal protective equipment (PPE)—nitrile gloves, face masks, hairnets, and coveralls. Gloves are changed between evidence items, and tools (swabs, tweezers) are sterile or disposable. Surfaces are cleaned with DNA-free wipes to prevent cross-contamination.
  4. Evidence Collection: Evidence is collected using matrix-specific tools: Biological evidence (blood, saliva): Flocked swabs with preservative tubes, dried blood spot cards.
  5. Trace evidence (fibers, glass): Adhesive tape lifts, vacuum samplers, sterile containers.
  6. Firearms/weapons: Gloved handling, plastic bags (to avoid moisture damage), tagged with serial numbers.
  7. Preservation & Packaging: Evidence is packaged in tamper-evident containers (paper bags for biological evidence to allow drying, plastic for non-biological). Labels include case number, evidence ID, date, time, and collector’s initials.
  8. Chain-of-Custody Tracking: A written log records every transfer of evidence from collection to lab analysis, with signatures of all individuals handling the item. Electronic tracking systems (barcodes, RFID) are increasingly used for real-time monitoring.

Key Features

  • Admissibility-Focused: Aligns with standards like SWGIT (Scientific Working Group on Imaging Technology) and FBI QAS (Quality Assurance Standards) to ensure evidence is court-admissible.
  • Contamination Mitigation: Strict PPE protocols, sterile tools, and separate packaging for different evidence types reduce cross-contamination risks by over 90%.
  • Consistency Across Cases: Standardized checklists and training ensure uniform collection regardless of investigator or crime scene type.
  • Auditable Traceability: Chain-of-custody logs and digital tracking provide a complete, verifiable record of evidence handling.

Scope & Applications

  • Homicide & Violent Crime Investigations: Collection of DNA, blood spatter, weapons, and trace evidence to link suspects to victims or crime scenes.
  • Sexual Assault Cases: Forensic medical examiners use standardized kits (e.g., rape kits) to collect biological evidence, ensuring proper preservation for DNA analysis.
  • Property Crimes: Collection of fingerprints, tool marks, and fiber evidence from burglaries or thefts to identify perpetrators.
  • Fire & Explosion Investigations: Secure collection of accelerants, debris, and explosive residues using specialized containers to prevent evaporation or contamination.

Training & Quality Assurance

Forensic personnel undergo regular training on standardized protocols, including hands-on exercises and written assessments. Quality assurance programs include blind proficiency testing, equipment calibration checks, and audits of chain-of-custody records to maintain compliance with scientific and legal standards.