What is the standard for determining whether a defendant is connected to a conspiracy?

"Evidence of even a slight connection, if proven beyond a reasonable doubt, is sufficient to convict a defendant of knowingly participating in an established conspiracy." United States v. Mares, 940 F.2d 455, 458 (9th Cir.1991). Moreover, such a connection may be inferred from circumstantial evidence. Id. "It is sufficient to show that each defendant knew or had reason to know of the scope of the conspiracy and that each defendant had reason to believe that his own benefits were dependent upon the success of the entire venture." United States v. Brown, 912 F.2d 1040, 1043 (9th Cir.1990) (internal quotations and brackets omitted) (discussing standard for determining whether defendants are connected to single conspiracy and not multiple conspiracies).