A Gaithersburg teen-ager was held in the Prince George's County Detention Center for seven weeks this summer after a court clerk failed to notify the center that his case had been dismissed.

Joseph Anthony Fletcher, a 16-year-old now living with his guardians in Gaithersburg, had already been held for eight weeks when, on July 9, District Court Judge Thomas R. Brooks dismissed the felony charge against him because the state had taken no action on the case.

The clerk handling the paperwork on the routine dismissal failed to scrutinize the youth's records closely enough to see that Fletcher was still in custody and thus failed to tell the jail to release him, according to administrative court clerk J. Michael O'Ferrall.

The error was finally discovered by public defender aide Joseph Gallagher as he made a routine check of the list of prisoners at the detention center. Gallagher said that when he noticed the amount of time Fletcher had spent in jail, seemingly with no action on the case, he helped obtain a release order for him on Aug. 24, nearly two months after the youth should have been freed.

"It's unfortunate all the way around; everybody just handled this thing too casually," said O'Ferrall, administrative clerk for the 5th District Court of Prince George's County, who was himself informed of the error as a result of a reporter's inquiries. O'Ferrall added that the clerk involved, whom he described as "normally an excellent employe," would have the incident recorded on her personnel record. O'Ferrall said he would also discuss the possibility of a reprimand with Administrative Judge Graydon S. McKee Jr.

O'Ferrall said the mistake that left Fletcher in jail was actually the result of several errors by clerks working through a process which should have released Fletcher on time. The situation was aggravated by the particular circumstances of Fletcher's case, and the fact that neither he nor his guardians knew enough about the judicial system to know where or when to inquire about the progress of his case.

"Nobody told me nothing," said Fletcher. "I heard I was dismissed the day they let me out, Aug. 24."

"I didn't even know we could get bond for him until about two weeks before he came out," added Bobbie Harring, Fletcher's guardian.

Fletcher's problems with Prince George's started in December 1980, when he was charged with three counts of breaking with intent to steal and malicious destruction of property at an Oxon hill storehouse. At the time, according to Harring, Fletcher was absent without leave from a forestry school, so he was taken to the Maryland Training School for Boys, where he remained until May.

Then on May 6, presumably owing to a juvenile record which Fletcher described as lengthy, including a number of escapes from juvenile institutions, jurisdiction for his case was waived from juvenile to circuit court by an order signed by Circuit Court Judge David Gray Ross.

Later that day he was taken to the Prince George's Detention Center, an adult holding facility located in Upper Marlboro. Bail was set at $5,000, which he did not meet. Because he was charged with a felony, Fletcher requested and received a preliminary hearing, which was held June 4 before District Court Judge Sylvania W. Woods who recommended that his case be held for a grand jury, court records show.

After 30 days, however, the state's attorney's office took no action on the case and, by law, that lack of action required that the case be dismissed. At that point the clerk's office should have sent the case back to court for a routine dismissal, notified the jail to bring Fletcher to court so he could hear the action on his case and then routinely ordered his release. According to O'Ferrall and court records, only the first of those three actions was actually done.

Detention Center files on Fletcher show no record of a July 9 action, according to Spokeman James O'Neill, indicating, he said, that the jail was never properly notified that Fletcher should have been brought to court.

"This place is very crowded," O'Neill said. "I'm happy to let them go."

A copy of Fletcher's file obtained at the district court clerk's offices showed the dismissal recorded on the jacket. Fletcher's name, with a penned-in notation saying "jail," also appeared on the clerk's office list of suspects up for dismissal, copies of which also go to the jail and the courthouse. But apparently no one at any of those places saw Fletcher's name and the fact that he was in jail.

The likeliest explanation, O'Ferrall said, was that Fletcher's name appeared on a list of those to be dismissed for lack of state action on their cases. Because most persons appearing on that list are either out on bond or were never jailed, the clerk did not think she needed to check Fletcher's status, said O'Ferrall.

"Of course, that's not by way of explanation," he added. "A person's liberty was at stake. It was carelessness. I don't think it was wanton; I don't think it was reckless."