Is there any case law where an attorney at law has been found guilty of misappropriating funds entrusted to the Attorney at Law by mistake?

Yes. As stated by this court in Most v. State Bar, 67 Cal.2d 589, 599, 63 Cal.Rptr. 265, 271, 432 P.2d 953, 959: "Misappropriation of funds entrusted to an attorney at law is a gross violation of general morality as well as professional ethics and, in addition, is likely to endanger the confidence of the public in the legal profession. It deserves severe punishment." In the present matter, petitioner's conduct clearly justifies the discipline recommended by the disciplinary board.