Does my wife need Police certificate again for interview? Thank you

If you sent one to NVC as part of CR-1/IR-1 processing, then it should not be needed for the interview. That being said, it would not hurt to have one handy at the interview just in case the counselor officer asks for it.

The NVC will send all documents to the embassy for the interview. Packet 4 will not only include a letter with the time and date of the interview but a list of all the documents that you have already submitted for your wife. We didn't get a second police certificate in Colombia because we had already submitted it, but we did have a black and white copy of it just in case. The embassy did end up getting every single document that was submitted to both, the NVC and the USCIS.

Diana