Forensic Psychology. Expert Testimony. Decisional Clarity.

Dr. Marcus Van Sickle

Board-Certified Forensic Psychologist providing competency, criminal responsibility, and expert consultation in complex legal matters nationwide.

Competency to Stand Trial • Criminal Responsibility • Risk & Threat Assessment • Specialized Expert Testimony

Why Retain Dr. Van Sickle

Dr. Marcus R. Van Sickle is retained in cases requiring clear, defensible forensic opinions, particularly where cognitive, behavioral, medical, and situational factors intersect.

Attorneys and courts rely on Dr. Van Sickle for his ability to:

  • Translate complex psychological and neurobehavioral findings into clear, legally relevant opinions

  • Address competency and criminal responsibility questions grounded in current forensic standards

  • Analyze alcohol, memory, sleep, and altered states with precision and scientific rigor

  • Explain counterintuitive victim behavior without speculation or advocacy

  • Provide measured, cross-examination-resistant testimony focused on the ultimate legal questions

Dr. Van Sickle’s approach emphasizes functional capacity, decision-making integrity, and risk, rather than overreliance on diagnostic labels or test scores alone.

Credentials & Training

  • Board Certified in Forensic Psychology (ABPP)

  • Board Certified in Behavioral & Cognitive Psychology (ABPP)

  • Certified Threat Manager (CTM), Association of Threat Assessment Professionals

  • MS and PhD in Clinical Psychology

  • Postdoctoral Master of Science in Clinical Psychopharmacology (MSCP)

Licensure & Scope

  • Licensed Psychologist (multiple jurisdictions)

  • Advanced Practice Medical Psychologist (MPAP) in jurisdictions where authorized by law

Core Forensic Evaluations

Competency to Stand Trial Evaluations

Evaluation of a defendant’s capacity to understand legal proceedings and to assist counsel in a rational and factual manner, consistent with jurisdictional standards.

Criminal Responsibility (Sanity) Evaluations

Assessment of a defendant’s mental state at the time of the alleged offense, including the impact of mental illness, intoxication, sleep-related conditions, or altered states of consciousness on criminal responsibility. Diminished capacity and/or general mitigation evaluations also offered.

Financial & Decisional Capacity Evaluations

Assessment of functional financial skills, decision-making capacity, and vulnerability to undue influence or exploitation, including in electronic and digital contexts.

Specialized Forensic Expertise & Testimony

Alcohol, Intoxication, and Memory

Expert analysis of alcohol-related cognitive impairment, blackouts, fragmentary recall, and the reliability and limits of memory under intoxication.

Victim Behavior & Trauma Response

Consultation and testimony addressing counterintuitive victim behavior, delayed disclosure, compliance, and behavior under coercive or traumatic conditions.

Sleep, Automatism, and Altered States

Evaluation of parasomnias, sleep-related behaviors, automatism, dissociative states, and other altered states relevant to criminal responsibility and behavioral control.

Violence Risk & Threat Assessment

Structured, evidence-based assessment of risk for violence, threat pathways, and behavioral escalation, including consultation in operational and preventive contexts.

Expert Testimony & Case Consultation

Dr. Van Sickle provides expert testimony in state and federal courts and consults with attorneys at all stages of litigation, including pre-charge, trial preparation, and post-conviction proceedings.

Marcus R. VanSickle, PhD, ABPP, MSCP
Dual Board-Certified in Forensic Psychology & Behavioral and Cognitive Psychology | PSYPACT Provider
In-person forensic practice in SC, TX, MD, VA, LA
Advanced Practice Medical Psychologist (RxP)
Defensible evaluations. Clear opinions. Reliable testimony