A CID number in jail is the Criminal Identification number a facility assigns to a person during booking, and it works as the single reference code that ties every record about that person’s time in custody — charges, court dates, housing, medical files, disciplinary history, commissary account, visits — back to one identity. Some jurisdictions call the same thing an inmate number, offender number, booking number, DOC number, or State Identification Number (SID); the Federal Bureau of Prisons calls it a register number. The label changes. The function doesn’t.
Where the Number Comes From
The CID is generated during booking, the intake process that follows an arrest. Staff search the person, photograph them, fingerprint them, and collect identifying details like date of birth and Social Security number. The facility’s records system then either issues a new CID or links the person to one already on file if they’ve been through the system before.
Fingerprints are what make the link reliable. During booking, prints are run through databases including the National Crime Information Center (NCIC), the FBI-maintained system that holds criminal justice records from agencies across the country. That check reveals outstanding warrants, prior arrests, and any existing identification numbers, which keeps the facility from creating a duplicate record and catches people giving false names.
Some facilities now add other biometrics at intake. Iris scans are used in some jails, and the FBI has invested in “Rapid DNA” technology that can produce a DNA profile from a cheek swab within hours of arrest. These data points attach to the same identification number, making the record harder to confuse with someone else’s or to falsify later.
How a Jail CID Connects to State and Federal Numbers
A CID assigned at a county jail doesn’t sit in isolation. When booking prints are submitted, they flow into the FBI’s Next Generation Identification (NGI) system, which assigns its own identifier called a Universal Control Number (UCN). Each UCN is tied to a single identity confirmed by fingerprint matching, and it acts as the bridge between the jail’s local CID, the state’s SID, and federal records.
When NGI returns a match, the system automatically runs cascaded searches against NCIC and the Interstate Identification Index to pull additional identifiers, law enforcement actions, and criminal history. Because those searches use the UCN from the biometric record, the responses are linked by an identifier established from positive biometric identification rather than a name match that could pull up the wrong person.
The practical effect: if someone arrested in one state has an outstanding warrant in another, the fingerprint-to-UCN link is what surfaces that warrant at booking. The same connection is how federal agencies verify whether a person they encounter has a domestic criminal record.
What You Use the CID For
If someone you know is in custody, their CID is the key to almost every interaction you’ll have with the facility. Knowing the number, or at least the person’s full legal name and date of birth, makes everything faster and reduces errors.
- Finding an inmate. Most state prison systems and many county jails offer online inmate search tools. The Federal Bureau of Prisons runs an inmate locator covering federal prisoners from 1982 to the present. For state and local records, contact the relevant department of corrections.
- Depositing money. Commissary accounts, which inmates use to buy food, hygiene products, and other supplies, are tied to the inmate’s ID number. In the federal system, deposits from family must be sent as money orders made out to the inmate’s full name and complete register number; personal checks are not accepted and will be returned. Many facilities also take online deposits through third-party services, which ask for the ID number or the inmate’s full name and facility location.
- Scheduling visits and messages. Video visitation platforms, phone systems, and secure messaging services usually require the inmate’s ID number to set up an account. Visits at many facilities have to be scheduled in advance, often at least one day ahead, through the facility’s designated platform.
The CID also lets you verify custody status, expected release date, and the facility where someone is being held. That matters when an inmate is transferred, because the CID follows the person even when the physical location changes.
What’s Public and What Isn’t
Not everything attached to a CID is public. Basic custody details — name, facility, charges, projected release date — are generally accessible through inmate search tools. Medical files, disciplinary reports, and investigative documents receive significant privacy protection.
At the federal level, the Freedom of Information Act lets the public request government records, but several exemptions apply to inmate data. Personnel and medical files are protected where disclosure would be an unwarranted invasion of personal privacy. Law enforcement records receive additional protection where release could interfere with enforcement proceedings, deprive someone of a fair trial, or endanger a person’s safety.
To request records about another person through FOIA, you’ll need identifying information including the inmate’s full name, date of birth, and register number. Requests for your own records require identity verification. Attorneys who need detailed inmate records for a case usually get them through discovery or subpoena rather than FOIA, since active litigation has its own disclosure rules.
When the Record Is Wrong
Mistakes happen. Data entry errors at booking, misattributed records from a flawed name-based search, or confusion between people with similar identifiers can corrupt what’s attached to a CID. The consequences aren’t abstract: the wrong criminal history at a bail hearing, denial of release for a parole-eligible inmate, or detention of the wrong person entirely.
Start with the facility’s records department. Most jails have an administrative process for reviewing and correcting records. Bring documentation that supports the correction — government-issued ID, court records, fingerprint comparison results, anything that demonstrates the error. The records department runs an internal review, and if the error came from an outside agency, such as a state criminal records repository or the FBI, that agency has to be looped in to fix it at the source.
If the error is in your state criminal history, you’ll likely need to contact the state’s criminal records bureau separately, because the jail’s CID and the state’s SID are kept by different agencies. Errors in the FBI’s federal records require a separate challenge through the FBI’s review process. The further an error has spread through interconnected databases, the more agencies you have to contact to fully clean it up.
Classification decisions inside the facility depend on these same records. The housing unit an inmate is assigned to and the security level they’re placed at are driven by the criminal history and behavioral record linked to the CID. An imported violent history can land a non-violent person in a high-security unit; a missing mental health record can block appropriate treatment. Eligibility for rehabilitation programs, education, and work assignments runs through the same records, and disciplinary reports tied to the CID affect good-time credit and release eligibility.
What Happens to a CID After Release
A CID doesn’t disappear when someone walks out of the facility. The number and its linked records become part of a permanent criminal history that surfaces during background checks for employment, housing, professional licensing, and other purposes. Employers in many states can access conviction records through state criminal records repositories, and the FBI’s database is used for background checks in fields like healthcare, education, and financial services.
Expungement or record sealing, where available, can limit public access. The specifics vary a lot by jurisdiction: what offenses qualify, how long you have to wait, and what “sealed” actually means all depend on local law. In some states an expunged record is physically destroyed. In others it stays in law enforcement databases but is hidden from public background checks. The identification number itself can persist in internal systems even after the associated records are sealed, since law enforcement agencies generally keep access for future criminal justice purposes.
If an old CID and its records are turning up on background checks after they should have been cleared, the correction process above still applies. You may also need to deal separately with third-party background check companies, which sometimes keep outdated information after official records have been updated or sealed.