Israel has sinned; yes, they have even transgressed my covenant which I commanded them: yes, they have even taken of the devoted thing, and have also stolen, and dissembled also; and they have even put it among their own stuff.
The burning of a criminal after his stoning was one way of emphasizing the wickedness of his crime (Leviticus 20:14; cf. Deuteronomy 13:15-16). It was a "disgraceful thing" (Joshua 7:15) to steal something under the ban (devoted to God).