Here is JH's explanation of how the first sketch came to be.
Delphi Murders CrimeCon Interview Transcript - CrimeLights
SGT. HOLEMAN: You can ask the tough questions, I’ll answer them. Again, it takes a lot of time. I’m not a sketch artist. The FBI actually–an agent from the FBI–did the sketch. And you know,
I think when somebody sketches it takes like, 10 minutes [shakes head ‘no’]. It takes several
weeks. But to get the information, to find the people that we believe saw that person that day near the time of the murders, that takes months. So we had to locate these people, interview them, find out who they really saw. Did they really see the guy on the bridge from the video, or did they see Mike out there helping search, or did they see somebody else out there helping with the search? So we had to identify those people, and once we felt like we identified the people that actually saw the guy on the bridge, then the sketch itself took, again, several weeks. They sketched it, looked at it, “No…that’s not correct”. I will say that she still–[
Clarification note: he quickly corrects his use of ‘she’ to ‘they’]—they, there’s a couple people— still aren’t convinced that’s the proper hat, but that’s the hat that the sketch artist could come up with as close to what the witnesses were describing. And I know the Superintendent [Doug Carter] said “Don’t focus on the sketch”, and we got a lot of calls on that. I think what he meant to say was…you know, where there’s four or five of us up here right now and if we pick somebody out of room right now and identify them to a sketch artist, there would be five different sketches. They’d have the similar features, as we believe this sketch has of the guy on the bridge, but they’d be a little different. So I think that what he meant is the person that did this heinous crime may not exactly look like that sketch. That’s what the person’s information and then the sketch artist had to take that information in and then put it on paper. So it’s not always going to be perfect, but we think that’s a really good sketch, and we think it’s really close to the person that we’re looking for on the bridge.