This morning I was playing halo reach. I completed the campaign and went back to the mission "lone wolf". Well first time I was on that mission I saw a dead corpse and just ignored it. But when I went back to it and I got a closer look at it when I tried to get more ammo and noticed that it wasn't just any corpse. It was either a ODST corpse or a spartan corpse. And not to mention in the halo books there were more Spartans then just noble team. I also noticed that Jun was the only spartan that did not have its own death scene. So was that Jun or someone else? I know Halsey was in the book after the fall of reach, but I think he stayed behind to protect Halsey.
Spartan Jun-A266 did not actually die on Reach. He left with Dr. Halsey to protect her as she traveled to CASTLE Base. In the books, Halsey later meets up with Fred, Kelly, Vihn, Isaac and Will, and she is no longer with Jun. At some point between leaving for CASTLE Base and that meet up at CASTLE Base, Jun leaves Halsey to go do something else (what is unknown). Sometime between Reach and Halo 4, Jun recruits Sarah Palmer for the Spartan IV program and begins to train her. Later, on the UNSC Infinity, he is shown giving the new Spartans a tour and fighting off insurrectionists that tried to take over during the comic Halo: Initiation. Jun was not any of the Spartans shown as dead in the Lone Wolf level.
You may notice I said "any" Spartans. In total, on the level Lone Wolf, there are 13 dead Spartans that can be found. They are an Unknown Spartan Unit, and their armor is randomly generated. The 13 dead Spartans are likely a reference to the number 7, as once you die, there will be 14 Spartans, or 7x2.