Sheriff Robert Pickell says the case "goes beyond torture."
Brandon Hayes, the boyfriend of the boy's mother, was arraigned Thursday on charges of felony murder, child abuse and other crimes.
Dominick was taken off life support Monday, a day after he was removed from the floor of an apartment in Argentine Township, south of Flint, Mich.
The sheriff says the beatings began a week ago, April 8.
Dominick's mother, Corrine Baker, tells TV station WEYI she was aware of the beatings but claims Hayes wouldn't let her out of the apartment to get help.