NEW : ` ` This is the saddest day in our nation 's history , '' the new president says . 'I am here to take you back to where we were before this happened and make sure that it never happens again. " The president was a former law professor and tax expert . The president died at a military hospital , the government says .
NEW : `` This is the saddest day in our nation 's history , '' the new president says . John Evans Atta Mills died a few hours after falling ill , his chief of staff said . The president was a former law professor and tax expert . The president died at a military hospital , the government says .