SA 220 statement is correct.
We can rely on joint auditor that doesn’t mean we can sign on his behalf. It simply means no need to recheck his area even if some entries originates from his area and he has checked it.
If joint auditor dies, either appoint new auditor for casual vacancy or give his work to other joint auditor, in either case work needs to be done, yes earlier documents, evidences, files can be used and relied upon.
And if the joint auditor dies after performing his work and signing the report and later it is found that the joint auditor did not perform the audit diligently, who would be held responsible in such a case?
As per SA 299, joint auditors are not jointly liable for work allocated to a particular auditor. Who would be held liable then?