Fairfax County education officials should have been more aggressive in investigating 1981 allegations of child sexual abuse against a school psychologist who later resigned and was arrested on similar charges, Superintendent Robert R. Spillane said yesterday.

Spillane also disclosed that the psychologist, Arthur S. Pomerantz, left the system last year under an agreement with his lawyers that deleted mention of the police investigation from his personnel file. Spillane said he will bar such agreements in the future and insist that any referral given Pomerantz mention his two arrests by Fairfax police.

Spillane said his office will handle future investigations of school employes suspected of criminal conduct. The personnel office previously had responsibility for such investigations. He said if he finds there is any evidence supporting the allegations, the suspected employes will be put on leave or removed from contact with children during the investigation.

As another safeguard, Spillane said, he hopes to have criminal record checks conducted on the Fairfax schools' 13,000 employes and on all job applicants.

Spillane and county officials have been investigating school officials' actions in the Pomerantz case after criticism that surfaced following Pomerantz' arrest on two child sexual battery charges this summer by Fairfax police. Pomerantz intends to plead not guilty to the charges, according to his lawyer, Mark E. Sharp.

Spillane, who took over the superintendency of the Washington area's largest school system July 1, told a news conference yesterday that he was not happy with the way officials had handled allegations against Pomerantz. "We need to handle those situations differently," he said. "We have to be more aggressive."

Coworkers have said they began telling superiors of their suspicions about Pomerantz as early as 1974. In 1981 police in Prince William County, where Pomerantz then lived, told Fairfax school officials they were investigating him on child sexual abuse charges based on an incriminating photograph. Police said they showed the photograph to Fairfax officials and that, while Pomerantz clearly was shown, they were unable to determine when the photograph was taken and thus unable to bring changes.

Pomerantz then went on sick leave while Fairfax officials looked into the matter, but he returned to his job after the investigation failed to turn up enough evidence to fire him, Spillane said.

Spillane said Prince William County police showed the photograph only to R. Warren Eisenhower, assistant superintendent for personnel, who did not know Pomerantz and could not identify him.

That statement was disputed by Prince William investigator W.P. Metheny, who said two other school employes who knew Pomerantz viewed the photograph and identified him as its subject. Spillane said Prince William police would not let Eisenhower have the photograph. They allowed him to photocopy it, but the reproduction was poor, Spillane said.

It was not until March 26, 1984 that other school employes were shown the photograph by Fairfax police and identified Pomerantz, Spillane said. Pomerantz was put on leave the next day, and resigned four months later.

Spillane said Fairfax school officials should have insisted on a copy of the photograph in 1981, and should have pursued their own investigation rather than waiting for the police to act. He conceded coordination between the police and the schools in 1981 "left something to be desired."

From now on, Spillane said, school employes will be urged to report evidence of child abuse to their superiors or to him. "We're not going out on witchhunts," he said. "We're not going to abrogate people's rights. But we have to assuage people's fears."

He said requests for job references on employes who quit under suspicion of child abuse "will be answered fully to ensure that such persons cannot go to another area or another system and work with children."