Serial murder remains one of the most extreme and least understood forms of criminal behavior, yet existing research has predominantly examined psychopathological, neurocognitive, and developmental risk factors in isolation, producing fragmented and theoretically incomplete explanations. This doctoral dissertation employed a mixed-methods retrospective archival design integrating crisp-set and fuzzy-set Qualitative Comparative Analysis (csQCA and fsQCA) to identify configurational profiles of psychopathological, neurocognitive, and developmental factors among the 20 most prolific serial killers in recorded history (N = 20), spanning 12 countries across five continents with confirmed victim counts ranging from 6 to 300. Grounded in the biopsychosocial model, diathesis-stress theory, Hickey’s trauma-control model, and Ragin’s configurational theory, the study systematically coded archival data across four domains: psychopathy (PCL-R proxy scores), Dark Tetrad traits (psychopathy, narcissism, Machiavellianism, sadism), neurocognitive indicators (prefrontal cortex dysfunction, amygdala abnormalities, traumatic brain injury, substance abuse), and adverse childhood experiences (ACEs). Results revealed that no single condition was individually necessary or sufficient for prolific serial murder, confirming conjunctural causation. The compound combination of narcissism and sadism emerged as the strongest necessary condition pair (consistency = 0.875). Five configurational pathways were identified via csQCA (solution consistency = 1.000, coverage = 0.812), converging with three fsQCA pathways (coverage = 0.710). High ACE scores approached sufficiency for prolific offending (fsQCA consistency = 0.925), while PCL-R psychopathy scores proved a poor predictor of prolificacy. Four distinct offender clusters emerged—Traumatized Narcissistic Sadists, Substance-Using Narcissists, organized methodical killers, and disorganized impulsive offenders—with Harold Shipman and Dennis Rader identified as theoretically significant outliers. Equifinality was confirmed: no single “serial killer profile” exists. Sensitivity analyses corroborated the robustness of all core pathways. The study’s signature contribution, the Configurational Model of Prolific Serial Murder, advances the biopsychosocial framework with empirical set-theoretic evidence and offers actionable implications for law enforcement profiling, forensic mental health assessment, ACE-informed prevention, and criminal justice policy.
Laszlo Pokorny (Fri,) studied this question.