A teenager has been charged over the sexual assault of a 15-year-old girl that was streamed live on Facebook.
Chicago police arrested the 14-year-old boy and charged him with aggravated criminal assault, manufacturing of child pornography and dissemination of child pornography.
Police say the boy was involved in the video which allegedly shows the teenage girl being raped - it was produced and broadcast mid-March.
Additional arrests are expected to be made as the investigation progresses as police have a number of suspects.
Police were not aware of the attack until the girl's mother approached Chicago Police Superintendent Eddie Johnson as he was leaving a police station on the city's West Side and showed him the video.
Mr Johnson was said to be "visibly upset" after he watched, both by the video's content and the fact that there were "40 or so live viewers and no one thought to call authorities."
Police have said the attack involved five or six males.
The girl's mother told Associated Press last month that her daughter received online threats following the attack.
The Chicago Sun-Times later reported that the girl's family had been relocated.