That would be right if Missouri (like the federal system) followed Pinkerton, but my limited research suggests that they do not. They seem to adopt the MPC approach and require that the defendant be an accomplice in the substantive crime, not simply a co-conspirator. Missouri statutes are available at http://www.moga.mo.gov/statutesearch/. The Missouri accomplice statute is Section 562.041 and the conspiracy statute is Section 564.016. Of course, I would be very interested to hear from anyone who practices criminal law in Missouri on the question of whether the state permits a conviction on a Pinkerton theory.