And the murderer must not be permitted to remain in the building indefinitely. It is my duty to apprehend him.

4 seconds sound clip from the Phantom of the Opera (1943) movie soundboard.

You can hear this line at 01:01:53.903 in the Blu-ray version of the movie.

Quote context

[...]

- There is an excellent suggestion in this, monsieur.

- You must reopen the Opera at once.

- But, monsieur, your orders...

- I'll countermand it. You must reopen.

- With Mademoiselle DuBois, monsieur?

- Of course. That should pacify this madman. And if he doesn't harm anybody, his being in the building doesn't matter.

- Christine DuBois must not sing, monsieur.

- What?

- And the murderer must not be permitted to remain in the building indefinitely. It is my duty to apprehend him.

- I don't understand.

- If Christine DuBois sings, that will satisfy the murderer, and he may never appear. So to lure him from his hiding place, someone else must sing.

- Are you suggesting that we reopen the Opera with a murder as an added attraction?

- I shall post police throughout the building, even with the chorus on the stage, with a special bodyguard for the singer.

[...]