Half past 12 or so, she was leaving the theatre with her mother when she said she'd forgotten something and went back to her dressing room. She didn't come down again.
6 seconds sound clip from the The Picture of Dorian Gray movie soundboard.
You can hear this line at 00:46:06.789 in the Blu-ray version of the movie.
Quote context
[...]
- When I found you'd locked yourself in, I assumed you knew about it.
- There'll be an inquest and you mustn't get mixed up in it.
- They don't know your name at the theatre, I suppose, and if they don't, it's all right.
- Did Sibyl? Tell me everything, Harry.
- It was obviously not an accident. Though I suppose it must be put that way to the public.
- So I have murdered Sibyl Vane. As surely as if I'd cut her throat.
[...]