I would also add to the above that, with all the arrests and Grand Juries convened in the last 2 years, LE may have gotten all they're going to find from the local gentry. If this was a professional hit, the person who ordered it probably doesn't live in the community, nor do the actual killers.
The only former locals who might know who called in the hit are now living in AK. There may be a few local drug/MJ traffickers in the area who also might know (probably why they busted the Eurys). Any of that info should have come out in the GJ, though. LE probably has an idea of who the boss(es) are and they'll have to rely on LE in the areas where they're located.
Why can't they call in members of the W family to testify in the GJ? Surely they've checked their phone records from that night and the weeks before. Are they waiting for a lot of physical evidence? They may wait a long time for that. Junk probably knows if he has to go up against an organized crime boss, they'll have a lot of high priced legal representation. They may just have to be satisfied in busting the top people on some other charge.
A little tidbit I found when searching about the Wag family and Procter and Gamble (something I heard in the beginning about the Wags being connected to the company by family), Nathan Estruth stepped down today as CEO of P&G (January 10, 2018) so he could run for Ohio Lieutenant Govenor, as running mate of Mary Taylor. Mary Wagner will succeed him. There are a few in this company with the name Wagner, I'm not implying their involved, but I thought it interesting,