Interview done, request for evidence?

[DungX 1]

i had an interview on december 17, 2013 after the interview i ask the office is everything ok? he said yes from what i see everything is good but i still need to go over your files. it was a large stack of paper that i saw in his hands. in 2007 i had an arrest for possesions of heroine so i had to wait 5 years to get my citizenship. in march 15, 2012 when i came back to the state at port of entry i was held in immigration for 3 months from vistiting my wife and child that lived in vietnam. in june 2012 i was released from immigration jail the judge granted me from REMOVAL. So my question is why do they still need an RFE (regquest for evidence)? i sent everything in and even hired an immigration lawywer. what do they need? do they need me to get a drug test or something to make sure i quit everything? i smoke weed hopefully dont dont require drug test.