Technically I think both parties would be guilty of murder, but that's specific to murder charges. For instance, getaway drivers have been charged with murder because the robbers they transport shoot someone.

That is specifically "felony murder", which wouldn't apply here (though conspiracy might?). Felony murder is the idea that you are guilty of murder if someone dies as a result of you committing another felony (sometimes from a specific enumerated list).

If you are a direct participant in the murder you might just get charged with it (perhaps as a conspirator which I think often has roughly the same penalties).