I am not sure if it needed to be the original or not but he took the original just in case. Just make sure to have copies of all your documents at home. Ask your recruiter and see if you can take copies. I know he had to turn in his work permit once he got his citizenship.
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Green Card application Sent/received: 7/1 - 7/5/16
Notice of Action: 7/11/16
Biometrics: 8/5/16 (Appoitment letter received 7/25)
Interview: 12/15/2016 approved on the spot.
Card received: 12/23/2016 (best Christmas present ever!)