PROVIDENCE, R.I. — Three people were charged with murder in connection with the discovery of a body under a newly poured cement slab beneath a deck in Rhode Island, officials said Tuesday.A grand jury indicted Steven Pietrowicz, 39, Michelle Morin, 40, and Corey Bickhardt, 34, on murder, assault, conspiracy and other charges, state Attorney General Peter Kilmartin's office said.Prosecutors say the suspects conspired to kill Domingo Ortiz, 60, of Worcester, Massachusetts, in May.