Markus Natten, the fictional character in the poem "A Death in the Desert" by Robert Browning, doesn't have a specific death date because he's not a real person. So, the answer to your question is simple: he never died because he never lived!
Related Q&A:
What is the death date of markus natten?-Well, I have no idea when Markus Natten passed away. It's not something that's commonly known to me or maybe not widely reported. You might want to check some reliable news sources or maybe do a detailed online search. It's possible that specific information about his death date could be found in certain official records or obituaries. Oh, I wish I could be more helpful on this one!