R.I. Gen. Laws § 10-10-11: Bonds and obligations not provided for void.

If any deputy sheriff, town sergeant, constable or the warden of the adult correctional institutions shall take or receive from any prisoner in his or her custody any bond, obligation, covenant, promise, or assurance whatsoever, to indemnify and save harmless the person taking the bond, obligation, covenant, promise, or assurance for the enlargement or ease of the prisoner, in any other form or manner than is prescribed by law for taking bail on mesne process in a civil action, or is prescribed in this chapter or chapter 12 of this title, every such bond, obligation, covenant, promise or assurance whatsoever, shall be utterly void.