There are a several possible explanations for a
criminal record that is not showing up in the data:
1) the subject was arrested but charges were never filed
2) the subject was arrested but acquitted of any crime
3) the subject was arrested but charges were withdrawn and reduced to something minor like a fine
4) the subject was arrested and charges are still pending
5) the subject was arrested and convicted but conviction records have not yet been uploaded into the public domain
6) the subject was convicted but was granted an expunction of the record
7) the subject was convicted but was granted a request to have the records sealed
NOTE: Criminal records rely on human action (i.e records to be uploaded) and there are oftentimes delays in the time it takes for records to become pubicly available.
Additionally, each jurisdiction may report in a different way and on different time schedules. There are literally thousands of different jurisdictions across the United States at the local, county, state and federal level.
Smaller jurisdictions may only report a few times per year and it is done as a manual process by hand; larger jurisdictions may report daily and have an automated process for it. The severity of the crime can also impact the time reporting takes, with minor infractions taking longer to report and more serious offenses being reported immediately. There are a lot of variables when it comes to the various jurisdictions and reporting standards.
Additional Resources: