The father-son like dynamic of the sniper team seems to modeled on the events of the DC sniper attacks ( Oct 2, 2002 - Oct 24, 2002). Also, like the events of said attack, a vehicle was used as a sniper's nest.
According to the jargon used by the FBI, these killers are referred to as LDSK or Long Distance Serial Killers:
- The public perception is that the FBI doesn't have an exemplary record with snipers.
- A sniper is a professional marksman and these persons do not fit the criteria.