What is the test for determining whether a witness was an accomplice to a defendant?

"When the evidence at trial would warrant the jury in concluding that a witness was an accomplice of the defendant in the crime or crimes for which the defendant is on trial, the trial court must instruct the jury to determine if the witness was an accomplice." (People v. Hayes (1999) 21 Cal.4th 1211, 1270-1271.) The court must further instruct the jury that the testimony of an accomplice is to be viewed with caution and that the defendant may not be convicted on the basis of an accomplice's testimony unless it is corroborated. (People v. Hayes, supra, 21 Cal.4th at p. 1271.) Where a codefendant's testimony exculpates himself but incriminates his codefendant, the jury should be instructed to view the testifying codefendant's testimony with caution only as it applies to the

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