[Dorian can look innocent even when he's guilty of murder (see: that time Sherlock Holmes interrogated him for the murder of Basil Hallward) but in this case, that innocent look of surprise—not at news of the Emperor's death, but the second he realizes that she is asking for an alibi—is %100 genuine.]

Oh! [But he isn't offended. He casts his mind back.] Handing in Bruce's paperwork at about dusk, drinks at The Brazen Turtle until maybe an hour past midnight? After that I slept. Alone. [A slight shrug of his shoulders; he can't offer her much more.] And I didn't see anything noteworthy while I was awake, sorry.