The reconstructionist's findings suggest this scenario:
DM went to his father's bedside, standing perhaps closer to head of bed, w the gun in his L hand as DM's left handed.
DM extends his L arm with gun in L hand, presses gun right up against eye or puts gun very close to WM eye. Then fires.
But DM fires gun w gun oriented to the LEFT on a 45 degree angle. That would feel ok to DM's lefthandedness perhaps.
But if he wanted it to look like his father had fired the shot -- the gun should have been fired on a 45 degree angle to the RIGHT.
That's why the cylinder gap and top strap GSR patterns seem upside down to this expert.
45 degree angle to the Right would match more closely the deceased holding the gun and firing.
DM probably figured: My dad is left handed. His left arm is extended. The gun has dropped below this extended left arm. Et voila -- the "perfect crime".
The absence of GSR on the left hand -- fits WM never having fired the gun himself. But GSR on his Right hand? The one tucked under the pillow? Is that from how DM fired the gun? Or did DM "manipulate" the death scene to make it look more like a father sleeping scenario and then seized by money grief and woes -- did suddenly reach for gun and kill himself?