I flew freight in and out of BTM many years back. There are two cemeteries on the west side of the airport and if memory serves me Holy Cross Cemetery is south of the terminal and Butte Aviation.
Looking at flightaware, this guy was coming from the southwest (from the Salmon VOR). No radar coverage below 10,800'.
The wind on the last METAR was
300@8 favoring runway 33. Could he have been on a 45 for a right downwind to runway 15, then just turning downwind he decided to make a 180 right over the Holy Cross Cemetery and enter a left downwind for 33, at which point the PC-12 got too slow?
I know, speculation, speculation. My Bad.
CC