Lauren Bush, 17, has been charged with assault, child pornography and false imprisonment.
The St. Mary's County Sheriff's Office said 17-year-old Lauren Bush and an unnaned 15-year-old girl - both students at Chopticon High School in Morganza, Maryland - recorded the assaults against the autistic 16-year-old victim on their cell phones.
Footage shows the suspects force the teen to walk on a partially frozen pond, which resulted in him falling through the ice several times.
Each time, police said, the suspects refused to help the boy out of the frigid water.
Sheriff Tim Cameron told ABC7 that the allegations leveled against the girls are among the most disturbing he has dealt with in his career.
He says that several times between December and February, the suspects preyed on the victim - assaulting him with a knife, kicking him in the groin, dragging him by the hair, coercing him to engage in a sex act with an animal, and forcing him to walk on the partially frozen pond.
Each time, police said, the suspects refused to help the boy out of the frigid water.
Sheriff Tim Cameron told ABC7 that the allegations leveled against the girls are among the most disturbing he has dealt with in his career.
He says that several times between December and February, the suspects preyed on the victim - assaulting him with a knife, kicking him in the groin, dragging him by the hair, coercing him to engage in a sex act with an animal, and forcing him to walk on the partially frozen pond.
'Another video depicts the male on an icy pond being told to continue to walk out further, actually falling in the water several times and pulling himself out,' said Cameron.
Bush, who lives in a rural part of the county south of Mechanicsville, knew the victim well, according to investigators.
Both girls are students at Chopticon High School in Morganza, Maryland.
'Who could harbor this ill will to do something so completely heinous?' said Cameron. 'I don't know. It's hard to fathom, really.'
Both girls have been charged with two counts of 1st degree assault, two counts of 2nd degree assault, soliciting subject in the production of child pornography and false imprisonment.
Bush was charged as an adult. She is being held at the St. Mary's County Detention Center. The other teen is being detained at the Waxter's Children's Center.
Video: Two Maryland teens admit to assaulting boy with autism
I understand that he is shocked, but colleagues of his have been doing things "so completely heinous" all over the country for I don't know how many years.
That's what you get when psychopaths, large or small, male or female, reign.