like what
A bullet will travel in a straight line, though it's unpredictable in its direction,which to my mind the first shot was from someone other than Sheila's own hand, because it hit the jaw-bone and deflected.
The second shot was by her own hand and because it was a low velocity rifle,markings around the area wouldn't be as prominent ( distinct patterns of gas and soot ) even though it was a contact shot,but the muzzle SHOULD have contained skin,flesh and blood.
Also, different weapons can be identified by the type of wound as well as whether that person had died before a second shot was administered.