As much as my curiosity would like to know more about BG and what happened out there, I'm not sure if anything they know could help identify him any more than what they've already shared. It would be nice to watch him walk in order to see what his gait is like and any peculiar things that stand out in his movements, to know how they were killed in order to know if they had suffered much or if there were similar unsolved murders around, to find out if they had gone through the creek or somehow gone over it, and many other things. The problem is that the anyone who would recognize him by his gait, mannerisms, word choice (if more audio were released), etc., most likely already recognizes him from the stills and audio that have been released. It's very possible that nobody recognizes him from the sketch because they're never like photographs, and I think that the more realistic they are, the less people are able to see someone with similar features but a slightly different look.
At this point, I'm not really sure what I'm doing here. I'm 99.99% sure that I've never met BG (even though he looks and sounds very familiar), LE has most likely figured out pretty much what happened and when, and I'm not sure that I can add anything other than more speculation about things that are unlikely to have anything to do with solving the case. Still, here I am anyway.