The nearest international airport is in Spokane, WA. There are multiple regional airports near the Pullman-Moscow area, including the Pullman-Moscow Regional Airport and the Lewiston–Nez Perce County Airport. Potential options would depend on what airline was being flown by the suspect's father. While most major airlines have flights to larger airports like Spokane International Airport, the regional airports are much more limited. For example, while United, Delta and SkyWest service Lewiston–Nez Perce County Airport, Horizon Air (under the umbrella of Alaska Airlines) is the ONLY commercial airline serving Pullman-Moscow Regional Airport. We'd have to know the airline his father flew in on to ascertain which airport he actually flew into. I feel sure the police and FBI have all that information.