I don't think anyone condones the lynch mob. But in reading on the case I think the man was guilty. He had previously been convicted of raping a black woman. He had been recently accused of 'peeping tom' activity.
I live in a rural county. The idea of an 'unknown man' who 'knew the accused would be passing by' is not reasonable. He couldn't be 'unknown' and also aware of a residents predicted where abouts. It's just not feasible. Nor is it feasible that on a death bed confession his name would still be unknown.
That said, I think that the guilty party was lynched in this case, not the norm in southern black lynchings.