I loved the blur effect in the first panel. Well done with the brush and lines to convey looking through a windshield. I also have to wonder, what would it feel like having your ears flap in the wind?
It sounds as if Cooper collects serial killers. Wonderful idea, would the police assume that the reason for a killing be anything but random if a known pattern killer did the job? It seems they would try to fit it into their profile rather than look for another motive.
Also in addition to calling each other names that would lead to violence for anyone else, Mulefoot uses Sammech's proper name. They are, as much as they can have some, real friends. This is bad. Sammech would not let friendship, love or anything else stand in the way of his sense of professionalism. Mulefoot is not ready to give up whatever claim he has on Brice yet. If he had Brice would have been a snack.
Best guess? A fights about to happen, or Sammech has Mulefoot back with a new serial killer, one who is attracted to very quiet girls.