The sexual abuse began in June 1982, the victim told police, when she was a 12-year-old student at Evangel Christian School in Dale City and was alone with her teacher in a classroom.

It continued over perhaps five more years, according to Prince William County police and criminal complaints filed in Juvenile and Domestic Relations Court in recent weeks. It is not clear whether anything specific prompted the victim to come forward with the allegations now.

Police charged Karold Stallard, 77, of the 1400 block of Forest Spring Lane in Earlysville, Va., with one count each of rape and forcible sodomy, two counts of aggravated sexual battery and two counts of indecent liberties by a custodian. He is being held in Prince William’s Adult Detention Center.

It is unclear whether Stallard has retained or been appointed a lawyer. A man who answered the phone at Stallard’s Albemarle County home declined to comment.

Three years after the classroom incident, another assault took place at the school, authorities allege in court papers. They say the last assault reported by the victim occurred in 1985 and that Stallard raped the girl at her home.

Police recently interviewed Stallard, court papers say. When talking with detectives, he “admitted to performing oral sex” on the victim in January 1985, according to the criminal complaint.

Police think there might have been more crimes dating until 1987, according to a news release.

The girl’s family went to school officials with the allegations in the 1990s, but they were not reported to police, said police spokesman Jonathan Perok.

In the 1990s, the school conducted its own internal investigation and later fired Stallard, Perok said. Although failure to report such a crime is a misdemeanor offense, a charge cannot be pursued now because the one-year statute of limitations has passed. School officials could not be reached this week.

Officials said the reportage of serious crimes years or even decades after the incident is becoming more common. The spike in Prince William’s crime rate last year was due to rapes that had occurred in past years being reported to police and prosecutors, they said.

The most serious crimes — including rapes, aggravated assaults and robbery — rose 8.96 percent last year in Prince William. Rapes that occurred in past years but are counted in the year they are reported accounted for 4.1 percent of the nearly 9 percent increase in the violent crime rate.

Police Chief Stephan Hudson said victims are less anxious about approaching authorities than they have been in the past.

“Overall, the general knowledge of the public . . . has been helpful in showing that it is safe and appropriate to come forward,” he said.

An Aug. 6 hearing has been scheduled for Stallard in Juvenile and Domestic Relations Court.