Bowhunting is not like hunting with a gun. If you take a shot at dusk, you had better be able to follow through and that means tracking in the AM if necessary. If you're not willing or able to do that, don't hunt in the afternoon! This applies to any deer, let alone a "massive" buck.
I agree with others, the arrow penetrated to the opposite side of the deer and probably hit shoulder bone. Most likely a dead deer within 100 yds especially since you did not push it.