Although Salvador Portillo-Saravia was being held by federal immigration authorities in 2003, they failed to enter his fingerprints into a national database before he was deported to El Salvador, immigration officials said Thursday. So seven years later, after Portillo-Saravia had sneaked back into the United States, his fingerprints were not in the database when he was checked by the Loudoun County jail.

The check came back “no match,” and he was released. A month later, Fairfax County police say, he raped an 8-year-old girl in Centreville.

The admission by an Immigration and Customs Enforcement official was in a letter sent to Rep. Frank R. Wolf (R-Va.) after Wolf had inquired about problems with the IDENT database, a nationwide collection of fingerprints and other biometric identification data.

Elliot Williams, ICE’s assistant director for congressional relations, wrote that “the agency policy to enroll the fingerprints in IDENT was not followed, thereby reducing ICE’s ability to thwart this terrible and tragic event.” ICE officials could not say why the prints weren’t entered in 2003.

The news that Portillo-Saravia had been released from jail in November after having been deported revealed a security gap: Many fingerprints taken before 2005 are not in the system.

Immigration officials said this week that they are taking steps to digitize all old “rolled ink” fingerprints that aren’t in the national database and that they are sending out monthly reminders to local jails to take additional steps when someone is suspected of being in the country illegally.

Portillo-Saravia fled the area after the sexual assault. After a manhunt involving federal marshals and local police, he was captured last month in Houston.

Portillo-Saravia’s preliminary hearing was set for Thursday in Fairfax juvenile court, but it was postponed because no court reporter was assigned to the case. The victim and her family were asked to return to the courthouse again in May.

Portillo-Saravia said nothing during the brief hearing and did not appear to make eye contact with the victim or her family.

Police said he had gone to the family’s home with a friend, on the morning after Christmas, and that the friend was dating the victim’s mother.

Portillo-Saravia, arrested early one Sunday morning on suspicion of being drunk in public, was back on the streets even though he had been checked through ICE’s Secure Communities program, in which the fingerprints of everyone who is booked into a participating jail are electronically checked against ICE’s national database. The database has 91 million sets of prints, ICE officials said, but was not fully operational until 2005.

Some prints taken before 2005 — officials aren’t sure how many — were handled the old-fashioned way, with inked fingertips rolled onto file cards or papers. Although all of Virginia’s jails participate in Secure Communities, many jail officials said they were unaware that people fingerprinted before 2005 might not be in the database.

“We have begun a methodical effort,” ICE Director John Morton said Wednesday after a news conference in Manassas, “to go through and digitize all the prints and put them through the system. That is the intent. But it takes time. And it takes money.”

Morton said he did not know how long it would take to enter the inked prints into the system. He said that prints are not in one central location and that officials are trying to determine the most efficient way to digitize them. ICE officials could not say Thursday what progress had been made to upgrade the database.

In addition to the electronic database check, jail officials can also make a manual request to ICE’s Law Enforcement Support Center or contact a local ICE field office if they suspect a prisoner is an illegal immigrant, ICE officials said.

After Portillo-Saravia’s case became public, ICE sent a teletype to all Secure Communities participants reminding them that “a ‘no match’ message . . . does not mean that the subject is lawfully present in the United States. Even in a ‘no match’ scenario, ICE may have an interest in the subject.”

That reminder will be sent every month to Secure Communities participants, ICE officials said. Some sheriffs said they do not have the time or resources to perform additional checks, particularly for the many prisoners who are being booked misdemeanors or lesser charges.