A Gaithersburg teacher's aide who worked part time as Santa Claus at a shopping mall has been charged with fondling a 14-year-old girl while she was posing for a holiday picture with a group of friends, Montgomery County police said yesterday.

John Steven Solyst, 27, of the 9400 block of Penshurst Court, was arrested Wednesday and charged with a fourth-degree sex offense, a misdemeanor punishable by a maximum of one year in jail and a $1,000 fine, said police spokesman George Ludington.

The incident allegedly occurred Dec. 7 at the Lakeforest Shopping Mall in Gaithersburg, police said. Solyst had been hired to act as Santa Claus by Cherry Hill Photo Enterprises Inc., a New Jersey-based company that has contracted with the mall for 11 years to provide holiday photo services, the mall's general manager, Barbara Kreuser, said in a statement.

According to a police official, Solyst is charged with touching the girl on her breasts and buttocks while she was "positioning herself" for a group photograph with five friends. The girl's parents reported the incident to authorities, police said.

A police official said the incident is still under investigation.

According to a Montgomery County school spokesman, Solyst has been working full time since Monday as a teacher's aide with special education students at Col. E. Brooke Lee Middle School in Silver Spring. He previously worked for the school system as a substitute aide, the spokesman said.

School officials placed Solyst on leave with pay yesterday after learning of his arrest. Solyst, who was released on his own recognizance, is scheduled for a court hearing Jan. 22.

In a statement, Lakeforest mall officials said they "were very surprised and disturbed by the recent allegation and subsequent charge." Alan Wechsler , chief executive officer of Cherry Hill Photo, said the company suspended Solyst last week after police told them about the allegation.

Wechsler said company personnel records indicate Solyst had worked in various capacities for the firm from 1983 to 1985.