1. A system comprising: a transponder associated with an offender; a radar module configured to determine a direction of a moving object passing within range of the radar module; a radio frequency identification reader situated near the radar module and configured to transmit an interrogating signal to the transponder and receive an identifying signal in response to the transponder receiving the interrogating signal; and a server configured to receive data from the radio frequency identification reader and the radar module through a network, transmit the received data to a web service through the network, and receive an alert from the web service that a monitoring rule of a plurality of monitoring rules associated with the offender was violated.