I looked at a news article this morning about fires at other Anadarko battery sites in CO in the last few years... there was a big one in spring 2017, I think, among others... Some have said that he might have intended to light the tank(s) on fire, and maybe was going to put both girls in one tank, but could tell by the "splash" :/ of the first one that there wasn't enough oil in that tank for a sufficient blast/fire, so he also used the second tank... :/ Would be backed up by him bringing along the gas can.... but it seems like such a reckless/dangerous plan, in addition to being monstrous...