Illicit trade generates billions of dollars annually for transnational criminal networks. Southeast Asia countries serve as transit points and destination markets for wildlife products that have been shipped across the global supply chains. A wide variety of animals are traded alive, dead, or as processed products. Part I of this paper provides a comprehensive analysis of illegal wildlife trades involving Southeast Asia countries, and Part II identifies the key factors in the illegal wildlife trade and evaluates the nature of the relationship between the key factors and the wildlife trade.