The unwillingness to talk mentioned by some outside observers is probably less a product of fear of witchcraft than of the wagon-circling of tight knit communities when an incident occurs which could show it in a negative light.
I was born to a farming family in what was then a fairly isolated highland area - arguments, and especially arguments about money, could last beyond the lives of the perpetrators; arguments about land, generations. And it's in the nature of rural life that the web of connections, loyalties and resentments could spread over a geographical area larger than any city. If you didn't want to get caught in the web, you didn't talk.
Don't think it had anything to do with witchcraft and many of the "facts" which link it to witchcraft are completely untrue. The two big ones for example are the crucifix cut into his chest which actually wasn't. There's no reports of that from the time. The other one is the similarities to a witch murder from the 1800s, which actually had almost 0 simlarities, except they both involved a pitchfork. I think a lot of the witchcraft hype comes from the biography of the copper written years later where he sort of glammed it up a bit in my opinion.
I did a podcast episode on it, despite the fact it's almost definitely got nothing to do with witchcraft it's still quite an interesting story. Poor guy though, sounded like he did his life right and then came to that end.