another meaning of 'boxing room'

Just because he’s charming? Look, we’ve seen this before, alright? We have the "D.N.A." - - Liv and I were in the "boxing room".

The speaker and Liv believes that 'he's a suspect. They already interrogated him. But the other detectives doubt that he committed a crime. So, the speaker is saying this dialogue when the other people is raising a question.

I googled it and found it on dictionaries, but I couldn't find a single answer that help me understand this dialogue.

Maybe it means interrogation room? Or is there another meaning of 'in the boxing room'?

Help me!

(My native language is not English. Please be kind to me. :-))

Solution 1:

I think this is just metaphoring Liv and "I" This may mean: Liv knows the thing that "I" know too