I happen to think that is actually a good question. Who would? No one!
Correct. No one would CHOSE to shoot someone twice if the were trying to make it look as if that person had committed suicide.............................HOWEVER, as the first shot didn't kill her, there HAD to be a second shot, but if he tries to make it look like a random and botched burglary he:-
A. Can't call the police to say his father has called to say Sheila has gone mad and....................
B . Doesn't have an alibi.
C. As the last person to see them alive he's in the frame.
D. Can't blame Sheila as he'd planned.