One of the two high school girls accused of assaulting a 16-year-old autistic boy in Southern Maryland has admitted to her role in the case, which has fueled outrage online and thrust rural St. Mary’s County into the international spotlight.

The 15 -year-old girl pleaded guilty to charges of second-degree assault and displaying an obscene photograph of a boy, according to The Enterprise newspaper in Southern Maryland. (The girl is a juvenile and has not been publicly identified by authorities.)

The second girl, Lauren Bush, 17, is being prosecuted as an adult. She’s been charged with first-degree and second-degree assault, and other charges. Both girls are have been released, but are under house arrest.

Bush and the other girl were arrested last month by the St. Mary County’s Sheriff’s Department, accused of assaulting the 16-year-old boy repeatedly from December to March. Their abuse was captured on the younger girl’s phone video, and shows Bush holding a knife against his throat, and the girls luring him out onto a frozen pond where the ice was thin.

The boy, however, has told his parents that the incidents were all part of a game and considers the girls his friends.

The 15-year-old girl’s attorney James Tanavage did not return an e-mail or phone call on Friday. John Pleisse, the St. Mary’s County Assistant State’s Attorney, did not return a voicemail, either.