Currently, there is no way to find out who deleted the story at Composer without directly asking to Arc team. However, if an article is deleted without someone's instruction or report in the newsroom, we need to know who deleted it so that you can figure out who is responsible. Sometimes, newsroom regards this situation as just Arc XP's system error which is not. Therefore, I think company's IT manager or someone who is in charge of Arc XP in the company(someone who is an admin) should have authority of finding what, when and who had deleted the story from Composer.