Networks within networks: using multiple link types to examine network structure and identify key actors in a drug trafficking operation

Understanding criminal networks can aid in the identification of key players and important relationships within the network. We examined multiple, directed link types in a criminal network. Eight distinct link types were identified, each one related to the exchange of a particular resource (e.g. drugs, money). The analyses focused on the eight link-type network layers and a merged network representing links across all eight layers. We were able to determine the link type of around 31% of the links, and found that nearly 50% of the nodes were involved in more than one network layer. This suggests that many actors contribute in multiple, diverse ways to the operation of the network. Actors were found to specialise in the exchange of particular types of resources, and also to specialise in the strategic position they occupied in the transfer of particular resources.