I doubt LE has narrowed down their search to one or two suspects. They might have a list, but if they do I imagine there are dozens, if not over a hundred, of possible suspects on it.
But I also doubt that LE is idle. The last I heard 1st Sgt Holeman is still the lead investigator. (I've also seen him listed as the 'lead investigator' on another case - the Flora fire, I believe - with two other detectives. So being a lead investigator is likely a supervisor with multiple cases to oversee.) I know I've read where there is still a team of ISP investigators on this and they probably still have a solid line of communication with the FBI and other agencies. How many times on here have we seen LE down to one detective after 6 months or a year in a murder or missing persons case. Here we are almost 3 years into this investigation and there is still a team working on it. And with over 42K in tips they need a team. I found a case the other day that was over 10 years old and the media stated LE had an unusually high number of tips - over 10K. This case was about 3 months over the 2 year mark with over 42K in tips. Just going over those once is a daunting task and I'll bet LE is going back to many of them more than once. I imagine there is probably a team meeting every morning with 1st Sgt Holeman - either in person or by phone or video conference - on yesterday's results and the day's plan of action.
I wonder how long the ISP can justify this level of manpower with a state-wide case load. For example, Marina Boelter, went missing on 31 Dec 2014 from Bloomfield IN but there was no ISP team working on her case 6 months after she disappeared. Sooner or later the folks in the state capital are going to want to see some solid results or scale back the manpower.