Case studies were conducted on eight serial killers in India who were inmates in central prisons of Kerala and Tamil Nadu. The study is a pioneering one on serial killers in the locale of the study. All available information about the lives of offenders were collected through multiple sources, including in-depth interviews with serial killers in the prisons, interviews of relatives of the killers, surviving victims, Investigators, crime scene studies, etc. The collected data have been chronologically arranged to construct biographies of the offenders. The rich biographies were carefully analyzed to construct an inclusive motivation model that can explain the process of individuals evolving into serial killers from a life-course approach. The motivation in each of the eight cases was explained with the proposed motivation model. The constructed motivation model is unique from the existing models, which were mostly rigid and, therefore, not applicable to cases outside the studies. The model proposes three critical determinants for explaining the evolution of a person into a serial killer, “nature,” “Deep Resting Life Factor,” and “key Incidents.” The study found a relatively short incident named “trigger” in the lives of six serial killers, which played a significant role in bringing out the dormant killer instinct and push the subjects toward the first murder. The comparative analysis of the motivation in different cases revealed that though there were recurring factors in the lives of serial killers, their interactions were more important than standalone factors. The study also found that there are no predetermined recipes for the making of a killer like some past researchers claimed.

案例研究是针对印度喀拉拉邦和泰米尔纳德邦中央监狱中的八名连环杀手进行的。该研究是研究区域内关于连环杀手的开创性研究。所有关于罪犯生活的信息都是通过多种渠道收集的，包括对监狱连环杀手的深度访谈、对凶手亲属、幸存受害者、调查人员、犯罪现场研究等的访谈。 收集的数据已按时间顺序排列安排构建罪犯的传记。对丰富的传记进行仔细分析，构建了一个包容性的动机模型，可以从生命历程的角度解释个人进化为连环杀手的过程。八个案例中的每一个的动机都用所提出的动机模型进行了解释。构建的动机模型与现有模型不同，现有模型大多是僵化的，因此不适用于研究之外的案例。该模型提出了三个关键决定因素来解释一个人演变成连环杀手的过程，即“自然”、“深度休息生活因素”和“关键事件”。研究发现，在六名连环杀手的生活中，发生了一个名为“触发器”的相对较短的事件，对于激发潜伏的杀手本能，将被试推向第一起谋杀案起到了重要作用。对不同案件动机的比较分析表明，虽然连环杀手的生活中存在反复发生的因素，但他们之间的相互作用比单独的因素更重要。