Three Secret Service officers with a high-powered video camera staked out the beach at Ocean City, Md., for three hours and 45 minutes on July 6, 1984. Crouching in the sand dunes, they surreptitiously observed and filmed a muscular man of 34 as he lay on the beach, soaking up sun.

Was this part of some secret antiterrorist operation? Was the target of the Secret Service surveillance a suspected assassin, perhaps a member of a Libyan hit squad?

Not quite. The object of all this attention was Robert Hambsch III, a member of the uniformed Secret Service and a union activist. The evidence of his afternoon at the beach was used by agency officials to fire him six months later.

The "crime" so painstakingly documented by Secret Service inspectors was that Hambsch, though on unpaid sick leave for a knee problem, had been forbidden to go farther from Washington than his Annapolis home and its environs. Service regulations require permission before officers leave their duty area. Ocean City is a two-hour drive east from Annapolis.

Summoned for interrogation later by a staff inspector, Hambsch was told to state where he had been from July 2 to July 8; he was told he could be "as vague as he wanted." Hambsch responded that he had been in Annapolis and nearby Cape St. Clair.

Hambsch requested the presence of an attorney or a neutral witness at his interrogation. This was refused. On the transcript of the interrogation, he wrote "Under Protest" beneath his signature. Hambsch was later fired for "falsification of facts" and insubordination. Hambsch appealed his dismissal to the Merit System Protection Board, claiming that his superiors were acting in retaliation for grievances he had filed against them. His appeal was rejected.

Hambsch then took his case to the U.S. Circuit Court of Appeals. He lost again, even though the court acknowledged that "one might be able to infer that high-ranking officers of the Secret Service were 'out to get him.' "

Court records reviewed by our reporter Jim Lynch reveal the basis for such an inference. They show that six agency officials met on June 19, 1984, to begin a formal investigation of Hambsch. Background information was provided to the officials by a senior staff inspector against whom Hambsch had filed a grievance two months earlier.

On June 29, Hambsch submitted a request to go to Ocean City, which was denied. On July 3, three agency inspectors staked out Hambsch's Annapolis home and noted that "no vehicle known to be used or owned by the subject was observed." Three other inspectors and a sergeant meanwhile took turns phoning the house, letting the phone ring 25 times on each call. They got no answer.

Two of the inspectors left Hambsch's home that day and drove to Ocean City. At 4:10 p.m., they spotted Hambsch walking from the beach. Three days later, the inspectors returned to Ocean City with a photographer and filmed him on the beach.

A Secret Service spokesman said the Hambsch investigation was "standard procedure to get sufficient evidence." Hambsch has asked the federal appeals court for a rehearing.