The beaten and partially-clad body of a girl who had been shot twice in the head and then left beside a road in Western Maryland was identifies yesterday as that of 16-year-old Lisa Ann Ryder, of Alexandria, who had been missing for the last three weeks, according to police.

Ryder's body had been left in bushes near the Sharpsburg National Battlefieled Park with a rope around her neck, according to her mother, Elizabeth Ann Richards.

Ryder, a sophomore at T.C. Williams High School in Alexandria, was last seen by her mother on the morning of Dec. 21, when she left for school, her mother said. Her body was found by a motorist two days later, police said.

Maryland State Police Sgt. Tom Moore said yesterday that tests are being conducted to determine if Ryder was raped. Richards said yesterday that police told her Wednesday that her daughter had been raped before being killed.

Last Friday, investigators released an artist's sketch of the dead girl and circulated it to area newspaters and magazines. Last Wednesday, a Hagerstown, Md., paper ran the sketch, and several people who said they lived in Fredericksburg, Va., and had seen the Hagerstown paper, called police to tentatively identify the girl in the sketch as Ryder, Moore said.

Police refused to release the names of the callers, and Richards said last night that she did not know their identity.

Alexandria police had listed the girl as a runaway, adding that she liked to frequent bowling alleys and other recreation centers in Alexandria, according to Alexandria Police Sgt. Archie Hall.

However, Richards, a veteran entertainer at various Washington Night clubs, disputed the "runaway" lable. "There were no clothes missing from her room, which she had just redecorated. We were friends; she confided in me. She didn't run away," Richards said.

Ryder was found wearing rings on several of her fingers, as well as a sweater stickpin with the letter "L," according to her mother. "For my birthday she gave me one just like it," Richards said.

Richards, who said her husband died more than 10 years ago, also has a son, 17.