Montgomery County corrections Director Arthur M. Wallenstein was on his way to Chicago last February when he received an alarming phone call. Craig M. Ricketts, a 35-year-old repeat offender awaiting trial on theft and burglary charges, had been mistakenly released from the Rockville detention center.

Wallenstein sent an urgent e-mail to the jail's ranking staffers: "This is a bona fide public safety emergency," he said. "A prisoner on the loose is and can be dangerous. . . . All else comes second until we have him."

Ricketts was recaptured four days later and returned to custody. But his accidental release was a public safety emergency about which residents near the Rockville jail never heard. It was one of five undisclosed incidents at Montgomery County detention facilities last year, and one of seven since 2000, according to corrections department records obtained by The Washington Post.

The reasons for the foul-ups varied. There were paperwork mistakes, miscalculated sentences and, in one case, a man released in place of a cousin with the same surname. Every inmate was recaptured within a few days. None is believed to have committed new crimes while at large.

But as Montgomery starts transferring prisoners this month to its new $90 million, state-of-the-art prison in Clarksburg, the trail of mistaken releases has raised questions about the county's ability to hang on to its prisoners.

Wallenstein said the mistakes are regrettable but not cause for alarm, given that 22,000 inmates pass through his jail and the adjacent processing center each year without incident.

"If anyone tells you we have a problem with improper releases, we don't," he said recently.

But at least one oversight could have turned into a tragedy.

In January 2001, Thomas Fenner was arrested on allegations of domestic abuse and jailed by the court for violating an order to stay away from his wife, court records show. (He later was acquitted, and his record expunged.) When Fenner arrived at the Central Processing Unit on a busy Friday night, the officer handling the case misread his paperwork and released him. Moments later, when she realized the mistake, she tried to find him in the parking lot. But he was gone.

"She aged 10 years in that moment," one corrections officer recalled. "She was terrified he would go back and kill his wife. She literally sat at her desk praying until she finally got word that they got him back in custody."

Corrections officials from other jurisdictions, as well as national experts, said the frequency of such episodes in Montgomery County should be cause for concern.

"It certainly is a red flag," said Alvin W. Cohn, a criminologist who has lectured on corrections at the University of Maryland and American University. "It should signal to the director that they have some questions to ask."

Wallenstein agreed that the number of errors in 2002 was unusually high but said that inadvertent releases are an accepted, if uncommon, occurrence in the corrections world. Given the number of people entering and leaving, especially in a county facility where no one stays longer than 18 months -- and most stay only a few days -- he said occasional mistakes are inevitable.

Prince George's County had three last year, and Fairfax County had two. The much larger D.C. corrections system has suffered from far more serious problems with record-related errors, including a spree of four wrongful releases during a six-day period last year. The cases eventually prompted an overhaul of the jail's records division.

Devon Brown, who has run the Montgomery jail and been the District's deputy corrections trustee, and is now commissioner of the New Jersey Department of Corrections, said the incidents might be unavoidable, but that does not diminish how serious they are.

"All it takes is one to go out and molest a child or injure someone," Brown said. "The public doesn't want to hear about the 8,000 inmates that got processed correctly."

The Rockville jail has been a longtime concern in such surrounding neighborhoods as Falls Ridge and Tower Oaks. And the opening of the Clarksburg facility doesn't mean a reprieve for residents.

Prisoners still will be taken to Rockville for processing before release. Authorities have historically assured community leaders that they are to be notified by phone if an escaped prisoner is in their midst (there has been one escape from the Rockville jail in the past 13 years).

One of those who is high on that call list, Susan Schoenfeld, a member of the jail's Citizens Advisory Board, said she wonders whether she should have been told about the mistaken releases, too.

"I tend not to be an alarmist, and I do have faith in the abilities of the people running the jail," Schoenfeld said. "So I would hope if they perceived there was a risk, they would have notified our community."

Wallenstein said the alarm he conveyed in his e-mail, describing the Ricketts release as a "public safety emergency," did not mean calls to local residents were warranted.

"Notifying the community would not be appropriate," he said. "The last thing you want is vigilantes out there when we have professionals who are dealing with it."

Getting released from the Montgomery County Detention Center is an elaborate process.

On the eve of a discharge, an officer in the records division checks sentence calculations to confirm that the prisoner was credited properly for good conduct. If an inmate was serving consecutive sentences, another officer reviews the file to make sure he or she finished serving every sentence. State and national databases are searched for outstanding warrants.

If all that is clear, a release authorization form is sent to the jail's front gate. Releases are at 10 a.m., a time selected because children are in school.

To keep an ex-inmate from wandering into surrounding neighborhoods, the jail provides bus tokens or cab fare back to the police station where he or she was booked originally. In most cases where inmates were mistakenly released, the error had occurred by the time they were escorted to a small, gray hexagonal room called "receiving and discharge," the final stop on the road to release.

Lisa Marie Kerrigan arrived there in October 2000, after officials failed to note that her sentences for petty theft were to be served consecutively.

Roosevelt Brockington was sent on his way before officers realized he was wanted in Fairfax County on theft charges.

When a discharge officer asked Varney E. Doe to recite his Social Security number, the officer was perplexed because it didn't match the one on Doe's paperwork. But when he asked his supervisor if there was a mistake, the answer was no.

Doe, who was being held pending trial on a theft charge (which was later dropped), was allowed to leave in place of his cousin, Roland Doe.

Once he was back in custody, the supervisor who signed off on his release was disciplined, and Warden William L. Smith sent a memo to his staff orderingofficers to initial every release form they read. Smith then placed final authority for all releases on the day's shift commander.

"I wanted more accountability," Smith said in an interview. "We needed to make sure people were reading the documents, not just looking at them."

Doe's was the first in the streak of five bad releases last year. To Smith and his staff, that is a disappointing statistic.

"When a mistake does happen, which really is very rarely, we are all very upset about it," said Carl Furr, who runs the records division. "Everyone is very much concerned that this person would go out and do something heinous. That weighs on all of us."