Now, we know that time travel is not one of the ingredients of this series, so the deceased could not be John's son who literally traveled from then to now.
One possibility might have been that John's son somehow inherited part or all of John's immortality - and lived, not aging a day, from 1913 until now, only to die riddled by bullets. Perhaps John's son had found his true love, the one who would set him free from his immortality.
Instead, the story took a more tame but still intriguing turn: this was a descendant of John's son who just happened to look like John's son. So we get get a nice episode tonight about another one of the many branches of John's family tree.
Along the way, we get some good thoughts about the immortality of art - John's a painter in 1913 - and some fine scenes in which John's art from 1913 shows up today.
I wished, again, that the show was more focused on this aspect of John's story than his police work.
On the other hand, there's more than enough of John and his many relationships and accomplishments through time to still make New Amsterdam an unusual series of lasting appeal.
See also New Amsterdam, 1,2,3 ... 4. Poetry and Parenthesis ... 5. Meets Mad Men ... 7. What Kept John from Dying? ... 8. New Amsterdam Bows: Lessons in Cons and Backsides
winner of the Locus Award for Best First Science Fiction novel of 1999
"delivers on its promises" - The New York Times
Silk Code trailer