Police Clearance Questions

[VBS]

Hi all....first time here so apologies if I am doing anything out of the ordinary. I am a US permanent resident but had been out of the country for awhile in South Africa. I have applied for the DS-117 to return and the petition has been accepted. I am now going about getting the SB-1 visa via the DS-260. My question is on the police clearances....as they make mention in their instructions to have clearances for anywhere you have lived for longer than six months. I have already got my clearance for South Africa where i have been traveling since i left the US so that is taken care of. Do i need to get a police clearance from the US as well or is this something the officer can lookup at the US consul? Then second I had resided in the US for 12 years prior to my trip to South Africa but prior to living in the US for those 12 years i lived briefly (2 years) in the UK. I had to provide a police clearance for the UK the first time i entered the US (12 years ago). Would i have to do this again or are the police clearances only for places i have been after my period in the US? I hope this makes sense and appreciate any help...thank you

[VBS]

I will go-ahead and apply for mu UK police clearance just in case it is needed. Can anyone tell me if i need a US police clearance when returning to the US or is this surely something they can lookup while at the interview on their own systems.
I am preparing to go for my SB-1 visa interview to return to the United States (where i have lived for 12 years) and need to know if i need a USA police clearance or will they be able to check this themselves at the interview. thanks for any input