Fingerprint expert Jean Escobedo testifies during a 2013 trial at Fairfax County Circuit Court. (Nikki Kahn/The Washington Post)

In the commonwealth of Virginia, it’s a crime to drive a school bus if you’re a registered sex offender. No surprise there, and not a likely scenario. But it’s only a misdemeanor, and there’s no requirement that school-bus-driving sex offenders be fingerprinted under state law.

The same is true for drunken driving of a commercial vehicle, or misdemeanor cruelty to animals: no requirement that the arrestees be fingerprinted. The realization that there are many crimes in Virginia that do not cause people to be fingerprinted was discovered by the Virginia State Crime Commission as it dug deeper into the question of why 750,000 conviction records are missing from the state database used to run background checks for gun purchases, court sentencings, employment and more.

The state enters conviction records into its database only when there are accompanying fingerprints — a rule aimed at confirming defendants’ identities. In some cases, fingerprints weren’t taken because of gaps in the arrest or court process. But in others, the prints simply weren’t required.

The State Crime Commission revealed the missing records in October, which included more than 300 murder convictions and 1,300 rape convictions dating back largely to 1999. Now the commission has devised a set of recommendations that could repair some big holes in the database and also amend gaps in the law so that everyone arrested for any jailable crime and many other misdemeanors will have fingerprints taken — and records entered into the state database — in the future.

Among the more significant steps suggested to repair the current database is to incorporate the fingerprints taken by the state Department of Corrections when convicted defendants enter prison or begin felony probation. Colin Drabert, the State Crime Commission’s deputy director, said the commission found that the commonwealth’s prison system has 500,000 sets of prints on file, which it provides to the Virginia State Police. The state police run the Central Criminal Records Exchange but state law has never incorporated the prison system’s prints into the records database, Drabert said.

The State Crime Commission is suggesting that the Virginia General Assembly amend two laws to enable the Department of Corrections to provide its fingerprints to the criminal database. Cross-referencing the existing 500,000 prints with the missing 750,000 records would mean “we may be able to whittle down a substantial portion of the missing felony convictions and probation violations,” Drabert said.

When a defendant is fingerprinted for a felony or a Class 1 or Class 2 misdemeanor at the time of arrest, the prints and ­charges are supposed to be sent electronically to the state police by the arresting agency or local jail, with a document-control number for each charge. When the case ends in a conviction or acquittal, the state courts send that information to the state police using the same control numbers. Fingerprints and charges are not expunged from the database even if charges are dropped. The database is not publicly accessible.

But fingerprints often aren’t taken at the outset of a case, particularly on arrests done with a summons such as marijuana possession, where the suspect isn’t booked into jail. And when a person goes to court and is convicted, or mails in a fine, their prints sometimes aren’t taken at the courthouse.

The commission said one option would be amending state law to require the collection of fingerprints when summonses are issued. But it acknowledged several challenges: that the technology may not be available for patrol officers to take 10 prints from every potential violator, that it would be time-consuming and that ink-card submissions may not be as accurate as the electronic Live Scan machines used at nearly all Virginia jails now.

In a report issued Dec. 3, the commission found that about 55,000 unique individual convicted felons are missing from the database. More than 2,500 robbery convictions and 1,500 weapons convictions are missing. The commission’s executive director, Kristen Howard, said that one way felonies can be excluded is when the prints are entered but only applied to one count among multiple counts filed and then that count ends up dismissed — or when new counts are added as part of a plea deal.

The direct indictment of defendants not initially arrested by police but simply charged later by prosecutors may have enabled some felons to avoid being fingerprinted. The commission calls for repeated checks by judges and court officials along the way to verify that the person is fingerprinted and in the system, right down to probation officers making sure that their clients are in the database before releasing them from probation.

The State Crime Commission first found the problem when looking at dispositions of marijuana cases. It discovered that the court system had reported 11 million convictions on all crimes dating to 2000 but that the database contained only 10.2 million convictions. About 90 percent of the 750,000 missing records lacked fingerprints, while about 10 percent were missing because of other errors.

About 35 percent of the missing cases were felonies. But the 65 percent that are misdemeanors can involve drug charges, assaults, drunken driving and family abuse, any one of which could be disqualifying convictions for someone seeking a gun or professional license. Police officials noted that missing fingerprints could also hamper law enforcement investigations when police find latent prints at a crime scene.

The State Crime Commission called for requiring state police to submit reports seeking to reconcile missing information from cases and to submit an annual report on the status of incomplete cases.

The commission also found that some fingerprints from completed cases may be on file in the relevant courthouses but were simply never submitted to the database, said Del. Rob Bell ­(R-Albermarle).

The commission is urging counties to try to match up missing convictions with fingerprints where they can, Bell said, because convictions may not be added to a defendant’s record without the fingerprints.

“The goal will be to stop these problems going forward,” Bell said, “and fixing it for all the cases who didn’t have prints done the first time.”