In People v. Esquivel (1994) 28 Cal.App.4th 1386, the defendant was convicted of felony murder based on his participation in the underlying robbery as an aider and abettor. (Id. at pp. 1389, 1393-1394.) Esquivel and two other men were at the home of an acquaintance when one of the men attacked and killed the acquaintance. Various items of personal property were stolen from the acquaintance's home, including guns that were found at the defendant Esquivel's home. (Id. at pp. 1390-1391.) Esquivel argued on appeal that the trial court "erred in failing to instruct the jury sua sponte that if he became an aider and abettor to a robbery after the victim had already been fatally wounded, he could not be found guilty of felony murder." (Id. at p. 1392.) The Court of Appeal agreed and reversed his conviction, holding Esquivel could not be liable for murder under a felony-murder theory if he formed the intent to aid and abet the robbery after the murder was committed and the jury should have been instructed accordingly. (Id. at pp. 1396, 1401.) The Esquivel court also held that the trial court had a sua sponte duty to instruct on the timing of his intent to participate in the underlying felony. (Esquivel, supra, 28 Cal.App.4th at pp. 1398-1399.) Analogizing to the law of conspiracy, Esquivel relied on People v. Marks (1988) 45 Cal.3d 1335, 248 Cal. Rptr. 874, 756 P.2d 260, in which the court stated, "'A conspirator cannot be held liable for a substantive offense committed pursuant to the conspiracy if the offense was committed before he joined the conspiracy. . The trial court, however, did not instruct the jury that it must find defendant joined the conspiracy before the murder. A trial court has a sua sponte duty to instruct on the general principles of law relevant to the issues raised by the evidence. . There was evidence suggesting that defendant did not join the alleged conspiracy until after the murder.'" (Esquivel, supra, 28 Cal.App.4th at pp. 1398-1399.) The Esquivel court also found that no instruction informed the jury that Esquivel, as an aider and abettor, had to have formed the intent to participate in the robbery before the murder was committed in order to be found guilty of felony murder. This amounted to a failure to adequately inform the jury of the relevant legal principles, as to which the trial court had a sua sponte duty to instruct. (Esquivel, supra, 28 Cal.App.4th at p. 1399.)