To Fairfax County police it was a clear case of one interest -- the public's right to know immediately about a crime -- giving way to another -- the expectation of a quick arrest that might have been made more difficult by publicity.

To Frances Hicks it was a case of police withholding information that might have endangered her teen-aged daughter.

Regardless of the interpretation, questions about the circumstances under which police withhold crime information have arisen following the county police's decision not to disclose, until a week after the incident, the alleged rape of a Fort Hunt High School sophomore during a football game at the school.

"Part of me says there must be a legitimate reason from their standpoint, to have that quiet time to gather evidence to build a case," says Hicks, the mother of a Fort Hunt cheerleader and the head of a local chapter of the National Organziation for Women (NOW). "But . . . I felt very unprotected because I didn't know that was occurring two blocks from my house, with my child going back and forth to school."

For police, the question of what to tell the public, and when, involves balancing the short-term desire to protect citizens by immediately releasing crime information against the long-term desire to apprehend a suspect and win a conviction.

Publicity can provide just the information a criminal needs to elude capture and can unnecessarily alarm a community, police say.

"It's a two-edged sword," said Lt. William White, head of the D.C. police public information division. "When information is disseminated about a particular incident, the individual may change his pattern . . . or he may go underground, and that makes it much more difficult for us to arrest him."

In the Fairfax case, police said that within a day after the Fort Hunt High sophomore was attacked Oct. 3, they had a prime suspect and a warrant for his arrest.

They delayed making the incident public and staked out the suspect's home 48 hours after the attack, expecting to make a prompt arrest.

The man did not show up, and the incident did not become public knowledge until five days later. The arrest was finally made the day after news accounts of the attack.

"This is an atypical case," said Fairfax police chief Col. Carroll D. Buracker. "In retrospect, information could probably have been released as early as two or three days after the incident. But we're dealing with a judgment call."

In Montgomery County, according to police department spokesman Cpl. Philip Caswell, "we expect a legitimate reason" if investigators ask that a crime not be made public.

"If we feel that releasing information is going to jeopardize a case, or if we are close to apprehending a suspect, we may delay," he said.

Because Washington area crimes are usually made public quickly, information delays can attract attention and anger people who feel they have been unknowingly exposed to danger.

Almost at the same time as the Fort Hunt attack, there were three incidents involving 5-year-old girls near the District's Bancroft Elementary School. Two were sexual assaults, and the third was described by police as an abduction "with sexual overtones."

When the public learned last week about the incidents, after the third in three weeks, parents and elected officials were sharply critical of D.C. police and school officials for not notifying parents.

Since publicity about those and subsequent attacks, D.C. officials have implemented new security measures at the city's schools.

Area police departments say there are no standard rules for deciding when an incident is to be kept from the public. The general policy is to release information about major crimes except in extraordinary cases.

Those include cases in which an arrest is imminent and publicity might warn the suspect, drug investigations in which undercover agents are still at work and might be endangered by publicity, cases in which the accuracy of a complaint or important details is unclear, and cases involving juveniles in which release of information might harm the victims.

There is another class of cases that may prompt secrecy but that area police officials do not mention: those that would generate great publicity, public anxiety and pressure for a quick solution.

In such cases -- which the Bancroft and Fort Hunt cases seem to be -- police may initially hold back information, hoping for a quick solution before the public can become alarmed.

"There is always that unstated factor -- public attention and public pressure," said Gary Hayes, executive director of the Police Executive Research Forum, an organization for police chiefs from large metropolitan areas.

"If a case is going to generate extreme pressure, it's easy for police to interpret nondisclosure on the grounds of operational reasons. You want to wrap it up and present it as a completed thing. . . . And you always think you're going to make that arrest tomorrow."