Why does Sherriff Smith tell Hiram to stay around town?

As they are discussing this, Sheriff George Smith calls to talk to Hiram. He asks Hiram about his call the week before and then if he has seen R.C. anywhere. Sheriff Smith also asks Hiram when he is to return to Tempe and Hiram answers he is leaving on Wednesday but Sheriff Smith says that Hiram is not to leave town for a while. Hiram may be needed for the case.