Check this out pls, I just don't get it?

[Aikuzo]

Check this out pls, I just don't get it?
The criminal guy named Mr. Halloran went to the girl's house to make the girl restore the painting w/ holes on it(at this time he said those holes are from a mouse bite)

NOW this is the conversation between the same girl and an FBI

Girl: Wait, those were bullet holes in Mr. Halloran's painting
FBI: What? What are you talking about?
Girl: I'm privately restoring a painting for Mr. Halloran. That's how we met. Oh my god... it was a russian painting.
FBI: He's been to your apartment?
Girl: Why, you think my roommates are in danger? ..... Oh, ~!
[Then they rush back in the apartment]

I just don't get this, how did she found out her roommates are in danger?

[Josef]

Probably from the tone of the FBI agent's voice.

And are you sure it isn't:
Girl: "Wait, those were bullet holes in Mr. Halloran's painting?" (with question mark)

She's just discovering that the mouse bites were bullet holes. Not a good sign.