CHICAGO — Authorities have issued an arrest warrant for another teenage boy in the sexual assault of a 15-year-old Chicago girl that was streamed live on Facebook and they expect to charge others, including one adult.

Police Commander Brendan Deenihan said at a news conference Sunday that investigators are searching for the 15-year-old boy, who is wanted on a sexual assault charge.

On Saturday, authorities announced the first charges in the case. A 14-year-old boy faces charges of aggravated criminal sexual assault and making and disseminating child pornography.

They say further charges are expected against an unknown number of others who were involved in the attack last month, which police said in the aftermath involved five or six boys or men.

Deenihan says multiple videos of the attack were made, not just the version that was streamed live. About 40 people viewed the attack live, and none of them reported it to police.

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