That's a pretty typical part of October, in my area at least, for mature deer to become less frequent or just simply disappear forever. What are the 10 miles like between your buddy's place and where it was supposedly killed? Was this the first year your buddy has seen it?
he got a few the year before. he was getting them up til oct 22nd 2016 and that is the last pic. in fact, pics two and three were from that day. it's the last he saw of him.