It is possible that LE has already spoken with a killer (or one of the killers). I doubt it, as the late release of the sketch and height/weight estimates hint otherwise. But it is possible.
The one thing to keep in mind is that the 18,000 tip number are not unique tips. There are likely thousands of tips that were made on one single RSO. Thousands of tips on RL. Thousands of tips across the next 3 or 4 most mentioned RSOs. Thousands of tips on the same known person put as a side-by-side with a BG image. Thousands of tips that said things like, "I think you should look in bars I think he is a drinker", "I think that accent is ...", "I think the hat he is wearing is brand ...", "i think he is a trucker", "I think he is left-handed", "I think there is a gun in his pocket", "I think he said (insert almost anything else) instead of down the hill" and so on. And a not small number of people tipping in ex-husbands, ex-boyfriends, neighbors they don't like, etc. just to cause those people trouble. And so on.
The reality is that the vast majority of tips came with no name or a name that came up previously tens, hundreds, or thousands of times. I would put money on the table that with the new batch of tips received that there are very few new names that LE received that they didn't get the first time around.