A Bethesda music teacher accused of sexually abusing a 13-year-old student and taking nude photographs of her had dozens and perhaps hundreds of photographs that depict teenage girls in various stages of undress, authorities said.

Detectives believe Carl E. Fritts Jr., co-owner of Bethesda Music, took nude photographs of as many as 100 students during the 13 years he taught guitar at the store, police said.

Fritts, 55, was charged Monday with child abuse, possession of child pornography and soliciting a subject for child pornography. Montgomery County police arrested him after the parents of one of his students, a 13-year-old girl, contacted authorities.

"There is really no way of knowing exactly how many students" were photographed, said Montgomery County police spokeswoman Lucille Baur. "But detectives believe it is over 50 and perhaps as many as 100."

John Lavigne, a Montgomery County public defender who represented Fritts at a bond hearing Wednesday, did not return a call yesterday seeking comment.

Fritts has been at Bethesda Music, in the 4800 block of Rugby Avenue in Bethesda, since 1991, police said.

Katie Gray, a clerk at Bethesda Music, said yesterday that Fritts taught guitar and was the most popular of the store's 15 music teachers. The store has about 350 students, said Gray, 17.

"He's really charismatic," she said yesterday in a telephone interview. "Everyone likes him."

Gray said that she took guitar lessons from Fritts for three years and that nothing inappropriate happened during those lessons.