If she is deceased from some freak accident or suicide, a decaying smell would be obvious by now for cadaver dogs to pick up, even if she is buried under dirt, especially without the proper embalming. Along with flesh flies swarming in the area.
Next, what else could hide the decomposing smell? Water... The body being under water or burned/cremation ....make your own assumptions...
If she is alive in iowa.. where can she be concealed witout anyone seeing or hearing her? In other cases, victims seemed to be closer to home, than found far away and found in another state seems rare.. unless it was a family member abduction. They seem to flee the area pretty quickly.