Donna Louise Gray BSc (Hons), MSc (MedSci), DipFMS, AfCGI

Background

Donna Gray is a forensic toxicologist and expert witness with more than a decade of experience providing independent toxicological opinion in medico-legal proceedings throughout the United Kingdom.

 As a member of Rimkus’ global Life Sciences team, Donna provides expert opinion in matters involving alcohol, illicit drugs, prescription medications, novel psychoactive substances (NPS), synthetic opioids, and other toxicologically significant compounds. Her expertise encompasses toxicological interpretation, evidential evaluation, impairment assessment, toxicity, causation, cause-of-death investigation, and expert witness reporting. She assists courts, coroners, tribunals, solicitors, and other legal professionals in understanding the significance, reliability, and limitations of toxicological evidence.

 Donna’s experience spans both ante-mortem (living) and post-mortem (after death) investigations, including complex, disputed, and analytically challenging cases involving a wide range of substances, including antidepressants, antipsychotics, benzodiazepines, cannabis, cocaine, heroin, MDMA/ecstasy and opioids, in addition to anabolic steroids, pesticides, antifreeze, yew berries and toxic gases such as carbon monoxide and nitrous oxide. Throughout her career, she has authored more than 15,000 toxicology reports and provided both oral and written evidential assessments, including chain-of-custody evaluations, continuity-of-evidence reviews, and forensic integrity assessments based on analytical data checks. She is recognised for translating complex scientific findings into clear, balanced, and defensible expert opinions that support informed legal decision-making.

 Donna has completed specialist expert witness training through Bond Solon, including Excellence in Written Evidence, Masterclass in Courtroom Skills, Witness Familiarisation, and Cross-Examination Testimony. She is committed to the highest standards of continued professional development, scientific integrity, independence, impartiality, and professional practice.

 In addition to her medico-legal work, Donna has served as an independent scientific advisor to UK Home Office Border Force, working collaboratively with the National Crime Agency (NCA) and police forces across England. In this role, she has provided specialist toxicological and occupational risk assessment advice relating to emerging synthetic opioids, including fentanyl and its analogues (e.g. carfentanil, acetylfentanyl, and furanylfentanyl), as well as other high-potency synthetic opioids, namely nitazene compounds (a class of synthetic benzimidazole opioids, i.e. isotonitazene, metonitazene and protonitazenenitazene). Her work has supported the development of evidence-based operational procedures, exposure control measures, and safe working practices for frontline enforcement personnel.

Her broader professional experience includes analytical method development and validation, assay development, laboratory governance, quality management, regulatory compliance, and scientific leadership within highly regulated forensic and life sciences environments. She has also led the design, implementation, and management of an integrated quality and health and safety system within a preclinical research organisation operating within the pharmaceutical and biotechnology sectors.

 Donna holds a high level of UK security clearance and combines extensive technical expertise with practical operational experience to provide scientifically robust, impartial, and defensible opinions in complex, high-profile, and legally sensitive matters.

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