Some who know how these doctors operate are saying these fetal remains most likely are from abortions he performed AFTER losing his license to so practice (i.e., illegally). Being an unlicensed abortionist, he would have been legally incapable of contracting for mortuary services. Being unable to legally dispose of the bodily remains of the fetuses he aborted illegally, he simply kept them.
I suspect those are the ones from after the Indiana law requiring mortuary services was passed. He probably never obeyed that law, since it would be an added expense.