Background and aim: Awareness of the causes and motivations of crime and especially murder and its prevention is one of the most important tasks of social institutions such as the judiciary and the police. Therefore, the main purpose of this study is to investigate the motives and factors of murder in East Azarbaijan province. Research methodology: This research is a quantitative content analysis and its statistical population includes all the cases of murder registered in the Provincial Intelligence Police during 2011-2011. All factors related to demographic data of the killers and victims including age, education, marital status, socioeconomic status, etc., as well as their possible causes and motivation were extracted and the data analyzed descriptively and analytically. Findings: The findings of the study showed that the causes and motives of the killing in East Azarbaijan province during the years 2011 to 2016 were mostly ethical issues, family disputes and strife. Conflict with the officer, financial disputes, gambling, fight and kidnap were the factors that had the least importance among the killers in the province. Conclusion: The results showed that causal factors such as ethical issues, family issues, mental disorders and issues in various domains (such financial, civil and agricultural) related to addiction, criminal history, theft, alcohol abuse, psychotropic drug use, youth, income level, low education and freelance work lead to the adoption of a strategy of strife, resulting in beatings and killing. Therefore, it is necessary to control and reduce the incidence of homicide in the province through cultural, sociological and educational programs.