Would they have only bugged the one room, or did the bug
only capture talk of revenge? Was there no talk about "the act(s)" committed? If so, why did they leave that out of the indictments? That would be very damning.
Why bug FW's home? The 4Ws weren't living there.
They had pieces parts of a silencer, that they'd found much earlier, from the former searches, but DeWine said the investigator's discovery of a homemade gun silencer in late October was a critical piece of evidence (@5:58) (but we have no searches of any properties, in the timelines, for the date it was discovered). If it's a human CI, they could have given up the silencer as a show of good faith (especially if they have a history, as many CIs do).
Folks have thought that the two families may have been into the drug business with one another. A CI that was trusted by the Ws, but was facing a sentence, would be a likely candidate for a CI, who could wear a wire (or place a bug).
Just some afternoon thoughts.