They were close; too close for her liking. Partners shouldn't be as close as these two were.
Alison Pearson knew Agent Faber was coming to town; she knew said agent had a thing for the feisty blonde marshal. She just needed to get her geeky partner out of the way. Then balance could be restored to the Albuquerque office.
The witness transport she called him to wasn't entirely bogus; there was a prisoner that needed transporting. It just happened to be a few hundred miles away from Albuquerque.
It wasn't like Alison had a thing for the taller marshal; quite the opposite, in fact. There should be no fraternization between Inspectors. Period.