Just a few thoughts: I assumed someone thought the first sketch looked more like the guy in the video. Which, now that I'm looking at it again, it is too pixelated to make out whether or not it is an older guy or a younger guy. The outfit made me think middle aged. So, perhaps stereotypes influenced the choice of the 1st sketch. I think at the time that the 2nd sketch wasn't the face they expected to see on that middle aged looking body in the video. Winter outfits by their nature conceal plenty. Still, both sketches or any additional sketches should have been released 2 years ago. It seems strange that they would point their fingers at the 2nd sketch now and tell us to ignore the first one. We don't know what the witness saw that "should be reported". Maybe the detectives didn't think it was related at the time, that something else shady might have been going down totally unrelated to the murder, but somehow something has recently came to light that made them decide he is the same man as the one in the video.
I did think it was strange that in the press conference they said that they are just getting started. That makes me wonder if their clues weren't getting them anywhere the last 2 years, but something has came up that has given them an actual direction to go in. New tip. New technology.
Someone mentioned they thought they saw a watch on the guy's right hand so that made them think he might be left handed. However, I am right handed and I've always worn my watch on my right hand.
Someone had made a comment about how the case might actually have been hurt by the video still somewhat. The argument is that someone might suspect someone and might have put in a tip, but then they discounted that suspicion because the person doesn't quite look like the sketch and the video isn't clear. Anyone with a suspicion should ask themselves the question, could this person look like the video image if they dressed differently? Also, as I was walking back from the gas station I considered how very different I am than my brother. I have gone on rail trails to bike and rollerblade, both in urban areas and in very rural areas and have done so alone. (I'm not sure I will anymore.) In contrast, my brother likes the air conditioning and probably will never be found on a wilderness trail outside of a couple state parks he rarely goes to but never alone. Going back then to why this guy was there in the first place. This person who did this was comfortable on that bridge and likely walks a fair amount outside. He isn't one of those guys who is afraid of dirt or sweat. I can see him being outside a lot. He may even walk that trail a lot or go to that area of the bridge regularly. He might walk alone a lot, either because he doesn't like to drive, doesn't have a car, or his car is unreliable.