It was deduced that "Jayden" was an "ice-man" from the northern mountains by the town scientist and healer, Talur. Data was in fact on a mission to Barkon IV to retrieve the radioactive remains of a probe that had crashed on the planet's surface.
Jayden was "killed" by a spear through his abdomen when attacked by an angry mob of villagers, blaming him for bringing them a plague. The "plague" was, in actuality, radiation sickness caused by the metal fragments in his possession.
He was buried in a marked grave beneath the town square after it was realized he introduced a cure into the water supply just before his demise. His body was transported back to the USS Enterprise-D, unbeknownst to the villagers. (TNG: "Thine Own Self")