All applicants and petitioners for immigration benefits must go through FBI fingerprint checks. This is one of four background investigations USCIS routinely conduct, with a focus on an individual's criminal records in the U.S.
Fingerprints collected at an Application Support Center (ASC) are submitted to the FBI's Criminal Justice Information Services. If the Integrated Automated Fingerprint Identification System (IAFIS) indicates that an individual does have a criminal record in the database, the FBI will send the matching record to USCIS and the entire RAP sheet is stored in the Biometric Benefits Support System (BBSS). USCIS adjudicators access BBSS to view these records and make decisions accordingly.
BBSS may have been or will soon be replaced by the Biometric Storage System (BSS).
People with prior arrests or charges should submit complete documentation and certified disposition records to avoid adjudication delays, even if they have been expunged or vacated. If you are unsure about a particular incident (whether it was considered an arrest or not), it is important to consult an attorney to ensure the accuracy of information on your application. Any misrepresentation about criminal history could result in denial of the case.
Given the importance of fingerprint checks, you should make every effort to appear at the ASC for biometric collection. If you cannot make it, you can and should reschedule an appointment by writing to the ASC. There is no guarantee your request will be accommodated, though. If you missed the fingerprint appointment (due to lost mail, for example), you may receive a Notice of Intent to Deny (NOID). You must respond quickly by contacting national customer service by phone, followed by a written explanation. A trip to infopass may be necessary as well. Keep detailed logs and records of your communication with the USCIS.
If your case has been pending for a number of years, you may be required to submit fingerprints multiple times during this process. In case of prolonged absence from the US, you may want to check your case status periodically to ensure that you do not miss an appointment. Unfortunately you cannot demand a FP notice from the USCIS before your departure, unless you have compelling reasons and can convince an officer during an infopass appointment.
Note that USCIS has basically stopped using printed photos you submitted with your application to produce new document, such as a green card or EAD card. So if you haven't had your digital photo taken at an ACS, chances are you will be asked to go before the card can be manufactured.
The FBI has been working on a multi-year, multi-million dollar project to improve and expand its biometric identification services. The program, named Next Generation Identification (NGI), will significantly advance current IAFIS capabilities and develop a future platform for multimodal biometrics. Essentially the system wants to move beyond fingerprints to include facial recognition, iris scan (eye), palm prints, voice, scars, tattoos, and more.
Another mission of NGI is to achieve better response times. For civil (non criminal) justice purposes, 10-print response time may be reduced from current 24 hours to 15 minutes (high priority) or 2 hours (routine).
Obviously NGI is still a "work in progress," and new functionality, if successfully developed, will be rolled out in phases. Also it is not clear what changes will apply to fingerprint check requests for immigration purposes. So for the near future, existing FP and biometric collection procedures established by USCIS will likely remain the same.