I don’t know. My guess would be that since it was CNN that found Stevens’ diary, it might have been them. Possibly al jazeera or the news guys from Lebanon who first announced that Stevens had been raped. Could have been Libyan press.
It could have been ansar al shariah itself since they do so love to film themselves in action and upload it straight to youtube.
Whomever it was, they were on the scene as it was happening. Strange we haven’t heard of any wounded or killed photo journalists.