See Pinkerton v. United States, 328 U.S. 640 (1946). A conspirator is liable for all offenses committed in furtherance of the conspiracy, even those of coconspirators.
In Pinkerton v. United States, 328 U.S. 640, 90 L. Ed. 1489, 66 S. Ct. 1180 (1946) the Supreme Court held that a party to a continuing conspiracy may be responsible 'when the substantive offense is committed by one of the conspirators in furtherance of the [conspiracy],' even though he does not participate in the substantive offense or have any knowledge of it. Id. at 647.
The liability of an accused for acts committed by co-conspirators is often called 'Pinkerton' liability, after the case in which the United States Supreme Court recognized the doctrine as part of federal criminal law and upheld it against a double jeopardy challenge. Pinkerton v. United States, 328 U.S. 640, 66 S.Ct. 1180, 90 L.Ed. 1489 (1946). The Court held that a conspirator may be found responsible for crimes committed by a co-conspirator, as long as the acts making up the crimes are reasonably foreseeable and are carried out in furtherance of the conspiracy, even though the conspirator did not participate ...