David Paulides is an investigator and writer known primarily for his work, including two self-published books, dedicated to proving the reality of the cryptid known as Bigfoot, and for his series of self-published books, Missing 411, in which he speculates about the disappearance of people in national parks and elsewhere.  Paulides attributes mysterious, unspecified causes to these disappearances, while data analyst Kyle Polich has analyzed Paulides' data and concluded that, statistically, these disappearances are not mysterious in any way.  In his pursuit of the cryptid known as Bigfoot or Sasquatch, Paulides self-published two Bigfoot-related books and created the research group called North America Bigfoot Search for which he serves as director.