A 26-year-old Mountain View man was arraigned on child pornography and cyberstalking charges after hacking a 16-year-old girl’s Facebook account and posting explicit pictures of her after she ended a relationship with him, prosecutors said Thursday. The 13-year-old girl refused Ridder’s request that she send him explicit photos, but Ridder threatened to show her mother other photos she had sent him “in a state of undress,” so she acquiesced and sent him more pictures, which he then sent to others, prosecutors alleged in a statement. Ridder was indicted by a federal grand jury on May 18 and has been charged with producing, distributing and possessing child pornography, cyberstalking, and coercion and enticement of a minor, prosecutors said.