This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.CHICAGO — A fourth suspect appeared in court Friday morning in the beating of a 15-year-old girl with special needs that was recorded on cellphone video and shared online. Chicago police said in a statement Thursday night that the 15-year-old was taken into custody and is charged as a juvenile with aggravated battery. Prosecutors in court Friday said the 15-year-old admitted to officers that she was part of a group of people seen in a viral video attacking the teen with special needs. She was allowed to go home with her mother after the court hearing, however, she is on electronic monitoring. Police earlier Thursday announced that three other girls ages 13, 14 and 15 were charged as juveniles, two of them with aggravated battery and one with mob action. In the video, the girl waves her arms as she tries to fend off her attackers. The video was posted by someone who described herself in the caption as a friend of the girl, who she said has a “mental disability.” Police say the girls had been showing the victim how to flash gang signs just before the attack in a South Side alley. In separate news conferences Thursday, the victim’s father, and relatives of her deceased mother, demanded that all of the attackers be brought to justice. The girls charged in this case are expected back in court in late August, as police continue to track down more people involved in the attack. The teen had been missing for several days before the video surfaced on Monday. Her father says he reported her missing on July 18. DCFS confirms taking protective custody of the 15-year-old, and has also revealed prior contact with her family and an ongoing investigation of neglect. A DCFS hearing is also being held Friday in regards to the 15-year-old. Police are also investigating whether the teen was sexually assaulted while she was missing.