What are the elements necessary to convict an individual under the aiding and abetting theory?

"The elements necessary to convict an individual under an aiding and abetting theory are (1) that the accused had the specific intent to facilitate the commission of a crime by another, (2) that the accused had the requisite intent of the underlying substantive offense, (3) that the accused assisted or participated in the commission of the underlying substantive offense, and (4) that someone committed the underlying substantive offense." United States v. Gaskins, 849 F.2d 454, 459 (9th Cir.1988). "[E]vidence of negotiations and illicit transactions both prior and subsequent to the specific sale described in the count can be used to establish ... guilt as an aider and abettor." United States v. Smith, 832 F.2d 1167, 1169 (9th Cir.1987).