- Now, I asked you once before, why did Duke Malloy kill his girl?
- I don't know.

5 seconds sound clip from the The Enforcer (1951) movie soundboard.

You can hear this line at 00:52:16.559 in the Blu-ray version of the movie.

Quote context

[...]

- Look, doc, I can't go with those guys. I got no family. I got no friends. I got nobody to take me out of here, and put me in a private place.

- I can't go. It's a trick. They're tryin' to get me. I won't go.

- Well, you don't have to go with them, but the city has to release you. You're perfectly lucid.

- If I walk out of here, I'm a dead pigeon. They'll get me.

- You tell me what I want to know, and I'll hold you as a material witness. If you don't, we'll let you go.

- Now, I asked you once before, why did Duke Malloy kill his girl?

- I don't know.

- What do you know about Angela Vetto?

- I never heard of her.

- Rico? Tony Vetto?

- I don't know any of them.

- OK, doc, kick him out.

- Now I done something. You can lock me up for assault.

[...]