I would imagine that a .357 or a .44 would be more than enough to take down a deer, depending on range, just as is the case for shooting a human. The story mentions that the pistol was a single-shot approved for hunting. A match or free pistol, perhaps? I still think that attempting a shot at some 200 yards after sundown, scope or no, was stupidly foolish. I hope there is some charge which can be brought? Manslaughter? Criminal stupidity?

200 yards with a scoped rifle in decent light is perfectly feasible, but I doubt that a scoped pistol would do the job at that range regardless of conditions. Longer barrels do make a difference, as does being able to use a sling in the prone position. No reliably accurate off-hand shooting at 200 yards, regardless of the movies!

BTW, you still haven't answered my question whether your firearm use every other day is by choice or necessity? Just asking.