|Season 1, Episode 9|
|Air date||15 April 2005|
Sniper attacks are occurring across L.A., but are all the shootings the result of one scattershot marksman or is a fad of sniper killings infecting L.A.? The team need expert assistance in trying to figure that out, and Charlie's theoretical models won't cut it without some first hand experience to bring them into line with reality.
A play on the concept of 'patient zero', the origin point of an infectious outbreak, whose identification and quarantine is often vital to the containment of a given condition. Here, Charlie attempts to develop comparable tracking algorithms.