United States v. DeSapio
In United States v. DeSapio, 435 F.2d 272, 282-83 (2d Cir. 1970), the defendants challenged the propriety of permitting a co-defendant to testify about statements made by Herbert Itkin, who had been working as an FBI informant for several years.
The Court held that Itkin was still participating in the relevant conspiracy, "even though he was currently reporting developments to the FBI and doubtless did not expect to be prosecuted.... Itkin, on his own initiative, entered into an illicit agreement with the defendants to carry out" the illegal venture. Id. at 282.
In DeSapio, the trial judge instructed the jury that if it found that "the FBI specifically instructed or authorized Itkin to participate in the Con Edison scheme from the very beginning, then it could determine that Itkin was not a conspirator as contemplated by the law." DeSapio, 435 F.2d at 283.