Chapter 10 is a flash forward chapter. That is kind of a unique thing in literature. Most authors or stories flashback in order to provide further character development. By flashing forward, Krakauer reminds his reader that Chris McCandless's story ends in death.
That is what the reader finds out in chapter 10. An unidentified hiker has been found dead in the wilderness of Alaska. The found man is the correct age to possibly be McCandless. The story is covered in the local Alaska paper and then picked up by the "New York Times." What that shows is that this found dead body has made national news. The last person to see McCandless alive, Jim Gallien, thinks that the found body belongs to McCandless, but he is not sure. The chapter does a nice job of building suspense, while at the same time reminding the reader that McCandless's ending is not a happy one.