1. A method of detecting suspicious activity, the method comprising: obtaining video data originating from at least one video camera that monitors a transaction area and that is positioned in close proximity to the transaction area, wherein obtaining video data originating from the at least one video camera that monitors the transaction area includes obtaining imagery of individual items tracked within the transaction area; analyzing the video data to track items including activity indicative of item presence involved in a transaction in the transaction area by automatically analyzing frames of video from the transaction area from at least one region of interest in at least a portion of the video data to identify a respective event indicating the presence of an item associated with the transaction; comparing the video analysis of the tracked items including comparing activity indicative of item presence to transaction data produced from a transaction terminal to identify suspicious activity; and automatically creating and maintaining an object model of items tracked using the imagery of each item, wherein creating the object model includes analyzing imagery of each item to identify and store visual features of each item according to item identification numbers.