I came across a curious fact yesterday. In Hirota v. MacArthur, the Supreme Court denied habeas relief to Japanese leaders who were tried as war criminals. The report than says “Justice RUTLEDGE reserves decision and the announcement of his vote until a later time.*” The * footnote says “Mr. Justice RUTLEDGE died on September 10, 1949 without having announced his vote on this case.” Think of this as the legal version of “The Mystery of Edwin Drood.”
I think that this the only public announcement of this sort of thing. Of course, a Justice who dies undecided on a case can be described in the same way, but the death is not mentioned at all when the case is decided.