Many of the organizations we know perform background screening for their staff and volunteers, especially those working with vulnerable populations. Here are a few resources shared by Ann Shanklin in Blue Avocado. She suggests doing a comprehensive screening that includes federal criminal, state/local criminal, and national sex offender screening.

FBI criminal record screening:
The Interstate Identification Index (III) is the national system that provides automated criminal record information, and is based on fingerprints. It will probably cost about $50 and typically the nonprofit pays the expense. If you have many volunteers (who, for example, work with young people) and you\'ll have many fingerprint checks done each year, you may wish to make an agreement with a specific fingerprint service (for example, many UPS stores do fingerprint checks). In some cases local police stations will do them at no charge. Ask a law enforcement agency or a nearby nonprofit for referrals.

Using a commercial background screening service:
A comprehensive screening will use a state database search, their own internal records, and a search of counties that have not reported (or not reported recently) to their respective states. A comprehensive search like this may reveal charges and dispositions not reported to the state or national repositories. Many insurance carriers have negotiated discounted rates on criminal history background checks for their insureds. Check with your broker or carrier to see what is available to your organization.