Police Clearance from other countries?

[gcinusa]

I'm going in for AOS/485 in the near future. I heard that I have to get Police Clearance from other countries that I have lived in the past 5 years.(if you have lived for more than 6 months in that country!) One Attorney confirmed that I need this if I go for CP...Need to know if it is needed for 485/AOS?

Is this necessary & if so can anyone guide me on how to get it from South Africa & Singapore?

Thanks a lot, folks!