if you go to INS website, you will see all the requirements before you get to interview stage. My parents had to submit following two among others...
i) police certificate from their local station
ii) clearance from Passport office
...apparently the document/clearance they obtained from Passport office is called "passport police certificate" coz their interview checklist indicates it has been submitted. See below cut n paste from their notice...
**********************************************************************
*Police certificates are required for each visa applicant aged 16 years or older, based on
where each applicant lives or has lived previously.
*Police certificates are also required from all other countries where the applicant has resided
more than 12 months. Present and former residents of the United States should NOT obtain
any police certificates covering their residence in the U.S.
*Generally, applications for police certificates should be made directly to the police authorities
in the district in which you resided. The police certificate must:
*Cover the entire period of the applicant's residence in that area, and
*State what the appropriate police authorities records show concerning each applicant,
including all arrests, the reason for the arrest(s), and the disposition of each case of which
there is a record.
*If you have any questions about where or how to apply for police certificates in other
countries, you may communicate directly with the U.S. consular office processing your visa
applications.
NOTE: Police certificates from certain countries are unavailable. Detailed information is
available from the NVC or the nearest United States immigrant visa processing post.
To download a form with complete instructions, please visit
www.ImmigrantVisas.state.gov.