The present study was performed to investigate the influences of rearing type, time of weaning, and maternal bond on the narcotic detection efficacy of police dogs. One hundred German shepherd dogs (52 males and 48 females) were utilized in this study. The study was divided into three experiments. Experiment I: dogs were divided into two groups with known previous history of rearing system; the first group received natural rearing (natural suckling). While the second group received artificial rearing. Experiment II: dogs were distributed into three groups. In the first group, dogs were weaned at 8 weeks, in the second group, dogs were weaned at 12 weeks and in the third group, dogs were orphans. Experiment III: dogs were distributed into two groups. The first group contained the dogs which were trained in the presence of their mothers, while the second group contained the dogs which were trained in the absence of their mothers. Results revealed that the narcotics detection trainability performance measures were significantly affected by the rearing system, time of weaning as well as the maternal bond, where the naturally reared dogs, dogs weaned at 12 weeks and those trained in the presence of their mothers showed better performance represented by the higher proportions of correct alerts and the lower false alerts, and chances and passes to detect the narcotics. These observations suggests that the events of the past (rearing type, extension of suckling and maternal bond) are correlated to and positively affected the future behavior and narcotic detection efficacy of police dogswithout the need for additional reinforcements. In conclusion, this study can be a base for further research toward reducing the expensive and time-consuming training practices required for adult working dogs to locate narcotics and other objectives.