He was probably helped in.

Did you look for the footprints ?" "I didn't think of that." Jack was speechless with scorn.
"Sat down and cried, eh ?" "I was dazed; I couldn't think.

But he couldn't have been killed by some other man.

There was no shot fired; I should have heard it." Jack moistened his lips.
"Lady, a knife don't make much sound either going or coming out--not much more sound than a whisper, but that whisper means a lot.

I got an idea that Dick heard it.