Don't recollect who told him about the broom or about the lie, but knows both.

Can't exactly say what'll be done to him arter he's dead if he tells a lie to the gentlemen here, but believes it'll be something wery bad to punish him, and serve him right--and so he'll tell the truth.
"This won't do, gentlemen!" says the coroner with a melancholy shake of the head.
"Don't you think you can receive his evidence, sir ?" asks an attentive juryman.
"Out of the question," says the coroner.

"You have heard the boy.
'Can't exactly say' won't do, you know.

We can't take THAT in a court of justice, gentlemen.

It's terrible depravity.