We don't know the specific laws of the time machine. One could assume that time travel technology simply moved people through time, not space (though, when you travel through time you are moving through space as the Earth is constantly moving through space). The Kansas cornfield where the murder victims-to-be show up could be the site of a secret mob time-travel facility 30 years later. Rian Johnson has hinted in an interview that all the time machines have fixed locations, so they cannot be changed to send victims into space, the sea, directly into a volcano, etc.