Interestingly, some sources are reporting he was shot with a improvised shotgun. These are very easy to make if you can acquire bullets -- a strong pipe, a nail and a cap are all you need. Where did he procure bullets from though, I wonder?
I work with an old guy who set out to make his own "shotgun" when he was 9. He took a piece of plumbing pipe with an end cap, drilled two holes near the end for the electrodes (pencil lead), and then packed it with a few hundred match heads and some BB's. He ran wire from the electrodes to his safety spot behind a berm, and touched it off with a battery. It blew apart his target, and he said the smoke could be smelled across the entire farm.
If a 9 year old could figure it out in the 1950's, I'm sure an adult, hell bent on murder, could figure it out today.
Looks very improvised indeed.
If you look at his hair, it is graying already quite a bit.
/smh
You can see the battery here: https://pbs.twimg.com/media/FXH0s0YXoAAehab?format=jpg