If you go back and listen to some of the interviews with investigators that took place in the first three months after the murders, they literally said this...expressed the exact thought you've written here. I'm thinking of one in particular with Sgt. Holeman where he said in the first two weeks they assumed it would be solved immediately and he couldn't believe it was two months on and it was still unsolved (though he still expressed optimism that it would be).
I think that local police generally have an idea of who the local "bad actors" are, and in this case it's my opinion that very early on some of the investigators were zeroed in on a particular sex offender from the Kokomo area who had an abduction/assault in his criminal history of an underage victim. I'm not going to put his initials here, though many of you who've been here from the beginning can guess who I'm referring to. I even think that the original sketch we saw may have been somewhat influenced by LE leaning in this direction. However, IMO this "good candidate" was eventually ruled out (perhaps by DNA, perhaps other things didn't fit) and they had to start over. I will say that if you read the details of the crime he was convicted of, and went to jail for, you couldn't NOT look at him seriously for the Delphi case. All MOO.
You have to remember this may not even be a case of sexual homicide, though I think the overwhelming gut response is that it is , and I wouldn't be any different in that aspect .
Unless its released that they were sexually assaulted, all we know is that the 2 girls were killed, how, and why are left to the imagination.
If this was an abduction murder for sexual purposes (which it may be, and probably is) then the individual you are talking about above is a great example of the type of person usually responsible
Though he was ruled out as a suspect, for whatever reason, I can say with a very high level of confidence that though hes not responsible , the individual you are looking for would not be all that different than the man you speak of .
This is again all speculative because of what we don't know .