Maybe Abbens has a health issue to deal with? You never know what the heck might be going on in his own life, and how an investigation such as this could be affecting him. I don't take it to mean that he isn't doing his job to the best of his ability - the man is only human, and he does have a life outside of work! And for all we know, it could well be that he is away because of work, for this case or some other.... I wouldn't put too much stock into his absence....
Abben's is Black Hawk's Chief Deputy Capt. of Evansdale & made spokesperson for the pressers, The sheriff is Tony Thompson. I haven't seen Sheriff Thompson but it seems clear to me that the FBI have the lead on the girls disappearance. jmo