But he knows who _did_ do it.
He's got all the details.

Some one has told him." Craven was trembling.

Olva pushed a chair towards him.
"Look here, you'd better sit down." Craven sat down.
"I know that some one told him," Olva said quietly, "because I told him." "Then you know who----" Craven's voice was a whisper.
"I know," said Olva, "because it was I who killed Carfax." Craven took it---the moment for which he'd been waiting so long--in the most amazing way.
"Oh!" he cried, like a child who has cut its finger.

"Oh! I wish you hadn't!" There was the whole of Craven's young struggle with an astounding world in that cry.
Then, after that, there was a long silence, and had some one come into the room he would have looked at the two men before the fire and have supposed that they were gently and comfortably falling off to sleep.
Olva at last said; "Of course I know that you have suspected me for a long time.

Everything played into your hands.