George W. Cookus is a distant cousin of John Cookus. I have a Xerox copy of the letter you cite and it clearly says John Cookus, not George Cookus. It was misfiled at the archives and I came across it by accident when I was searching all the Cookus files. We know from family history that John died on 4 May 1863 from consumption. His widow and children ended up living with relatives (his youngest son was my great grandfather). This is a real puzzle.