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Legal Chain-of-Custody

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What is chain-of-custody?

Chain-of-Custody (COC) is a documentation trail that demonstrates possession, control, and integrity of a sample at all times. COC is established when:

  • The sample is in a person’s physical possession
  • The sample is in view of the person after being in possession
  • The sample was in physical possession and then locked up to prevent tampering
  • The sample is kept in a restricted, secured area

Each transfer of custody must be documented to provide evidence that the sample has not been tampered with or altered in any way. Documentation also ensures that proper sample handling has been maintained and is used to track samples through collection, processing, analysis, and eventual disposal. Each sample will be labeled and assigned a unique identification number. Documentation of temperature control, storage conditions, and tamper proof seals are critical to maintain the integrity of a sample. Documentation for a legal sampling event will include photographs, videos, field notes, and COC forms. Unequivocal documentation is necessary to meet quality control and data defensibility in legal proceedings.

General requirements of COC forms include the sample collector’s name and signature, mailing address and phone number, the name of project manager or person who will receive data, the analytical laboratory’s name and city, and description of each sample (unique identifier, matrix [i.e., soil, water, gas], date and time of collection, and type of analysis required) (Figure 1). The COC must be dated with signatures of individuals involved in the chain of possession. Although environmental laboratories routinely use COC to track samples, it may not satisfy the additional details required for litigious investigations. To meet the requirements of legal COC it is recommended to refer to the ASTM Standard Guide for Sample Chain-of-Custody Procedures (ASTM D4840-99) (ASTM, 2018) .

Figure 1: Chemistry Matters Chain-of-Custody Form
Figure 1: Chemistry Matters Chain-of-Custody Form

Why is it important?

The purpose of following Chain-of-Custody procedures is to provide evidence that all samples during collection, transportation, and storage were handled only by authorized personnel and were not available for tampering prior to analysis. COC documentation may serve three purposes 1) analytical instructions between sample collection personnel and the analytical laboratory, 2) record of samples provided to the laboratory, 3) documentation for litigation cases.  For legal investigations, all personnel involved with the custody of samples should have prior training on COC procedures. Any break in the chain-of-custody can invalidate the samples as evidence.

  • Legal Sampling
  • Study Design
  • Data Analysis and Visualization
  • Data Wrangling
  • Multivariate Statistical Analysis
  • Principal Component (PCA); Hierarchical Cluster (HCA)
  • Science Communication
  • Data Science/Big Data
  • Multidimensional Gas Chromatography (GC×GC)
  • Source Apportionment
  • Chemical Fingerprinting
  • Diagnostic Ratios
  • Clandestine Laboratories
  • Fate and Transport
  • Soil gas sampling
  • Surface casing vent sampling
  • Forensic Genetic Microbiology
  • Arsonous Wildfires

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Chemistry Matters Consulting Services and Expertise

From sample collection to data analysis, the Chemistry Matters team ensures that the entire process is performed with the requirements necessary to overcome legal scrutiny. Executing and documenting an unbreakable chain-of-custody is vital for the legal defensibility of evidence in environmental forensics and arson investigations.

Environmental Forensics

Protocols required for an environmental forensic investigation are more stringent than a typical environmental investigation  (Richards and Sandau, 2014) . The Chemistry Matters team has expertise in designing and implementing a legal COC protocol. This includes rigorous documentation of sample integrity, training personnel on sample control, and choosing a laboratory with stringent quality guidelines. Chemistry Matters has assisted clients in determining appropriate data quality objectives (DQO), developed legal sampling plans (SAP) and has strategic partnerships with laboratories accustomed to the legal COC protocols.  Chemistry Matters provides third party data validation services to provide another layer of scrutiny to ensure all data is valid for its use.

Arson Investigations

The academic and professional background of the Chemistry Matters team provides clients with the expertise required to execute legal COC protocols for evidence collection and management. The evidence collected during an arson investigation must be handled only by authorized personnel. When it is not in direct possession of the personnel it must be stored in a secure location. When the possession of the evidence is passed from one person to another, it is recorded on the chain-of-custody documents. Additional sample security measures such as tamper-proof labels on sample containers and temperature control monitoring should also be documented through COC.

Expert Services

Our scientific background and experience with legal COC provides clients with a consultant that understands sound scientific principals and legal evidence management. The consulting services of the Chemistry Matters team include investigation planning, data analysis, and expert witness services. With data and findings that hold up to legal scrutiny, Chemistry Matters helps litigators confidently build their case.

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