He could imagine no reason for it.
Tom had been a bully at home, but outside he was on jovial terms with his fellows--except only himself.

He had to acknowledge to himself the seeming justice of the popular feeling.

If any man in Sark might, with some show of reason, have been suspected of the killing of Tom Hamon, it was himself.
Once, by reason of overmuch groping in the dark, an awful doubt came upon him--was it possible that, in some horrible wandering of the mind, of which he remembered nothing, he had actually done this thing?
Done it unconsciously, in some over-boiling of hot blood into the brain, which in its explosion had blotted out every memory of what had passed?
It was a hideous idea, born of over-strain and overmuch groping after non-existent threads in a blind alley.
He tried to get outside himself, and follow Stephen Gard that night and see if that terrible thing could have been possible to him.
But he followed himself from point to point, and from moment to moment, and accounted for himself to himself without any lapse whatever; unless, indeed, his brain had played him false and he had gone out of the house again after going into it, and followed Tom and struck him down.
With what?
The Doctor said with some blunt instrument like a hammer.
Where could he have obtained it?
What had he done with it?
The idea, while it lasted, was horrible.

But he shook it off at last and called himself a fool for his pains.

He had never harboured thought of murder in his life.