A man told police that his Smith and Wesson revolver needed servicing, so he brought it to work at Georgetown Preparatory School on Wednesday and put the unloaded, holstered weapon on his desk.

Authorities charged Stephen P. Lafferty, 51, of Frederick with possession of a dangerous weapon on school property and one count of possession of drug paraphernalia, officials said. Lafferty was described as a staff member and is not a teacher.

Police were called to the school campus, at 10900 Rockville Pike in Bethesda, about 1:50 p.m. for the report of an employee with a gun.

After officers took Lafferty into custody, they searched him and also found that he carried drug paraphernalia, Montgomery County police said.

“There [were] no threats made; at no time were any students, faculty or staff in danger,” said Patrick Coyle, a school spokesman.

He added that the school’s headmaster sent a letter to parents Thursday.