kpix 5's julie watts shows us who he is: einkaufszentrum. >>> outrage on social media, it's swirling around the man behind the 24 hour artist collective known as the ghost ship. julie watts shows us who he is. >> reporter: understandably, the emphasis is on the victims right now. authorities focused on recovery to bring closure to loved ones. but soon the investigation will ask, who is responsible for this horrific tragedy, and certainly investigators will want to speak with the building's master tenant. [ screaming ] >> reporter: he goes by derick ion. reportly the head of the ghost ship artist collective. a live-work warehouse and the scene of the deadliest fire in oakland's history. >> [ screaming ] >> reporter: in some youtube video his behavior appears erratic. in others, like this one, where he talks about what he calls the festival culture, he offers a rambling description of his desire for a simplistic earth. >> farm and build houses and evolve and oh my god, that's a life. there we go. >> reporter: this video from 2012 depicts an elaborate concert called living dead complete