These sections of the MCL might help:
700.5504 Power of attorney not revoked until notice.
(1) The death of a principal who has executed a written power of attorney, durable or otherwise, does not revoke or terminate the agency as to the attorney in fact or other person who, without actual knowledge of the principal's death, acts in good faith under the power. An action taken as provided in this subsection, unless otherwise invalid or unenforceable, binds the principal's successors in interest.
700.5505 Proof of continuance of durable and other powers of attorney by affidavit.
(1) If an attorney in fact acts in good-faith reliance on a power of attorney, durable or otherwise, and executes a sworn statement stating that, at the time of the action, the attorney in fact did not have actual knowledge of the principal's death, disability, or incapacity or of the power's termination by revocation, the sworn statement is, in the absence of fraud, conclusive proof of the power's nontermination or nonrevocation.
I read these sections to say that if you have actual knowledge of the principal's death, you can no longer act in good faith under the POA.
CRCM, CAFP, DAD