He does not yet know about the party's involvement in the incident. He does however suspect that Oriann may be somehow be involved. He does not elaborate on why.
If the players explain to him the truth of the library, he will offer/ask to have them along in the next step of his investigation.
>If you happen to have more questions, in evenings can usually be found at the bar here -he pulls out a notebook and writes down the address of a bar-.