R.I. Gen. Laws § 6-36-19: Proof of conspiracy or combination.

In a prosecution under this chapter, it shall be sufficient to prove that a conspiracy or combination exists, and that the defendant or defendants belong to it or acted for or in connection with it, without proving all members belonging to it, or providing or producing any article or agreement or any written instrument on which it may be based, or that it was evidenced by any written instrument at all.