I know I indicated readiness for laying out some specific plans of action, but I find myself with further thoughts about Cheryl's theory
For the first, let me play devil's advocate a bit with elements of the theory. One permutation holds that one party (the LK) had the Bridgetower Inn observed, and robbed Sir F when he was going to make the drop. Then a second party (3-M guy), also staking out the environs near the inn, sees Sir F robbed and murders him. Then the next morning, a
third party (Morgathians, say) staking out the Bridgetower Inn sees the Baron flee and sets up the ambush. Now I know I'm being difficult for the sake of argument, but three separate unaffiliated stake-outs of the inn during, say, an eight hour time period is just too friggin' many stakeouts. Coulda happened, true, but it frankly beggars the imagination.
My own inclination is to think that at least two of these parties must be in cahoots.
Then there is the matter of Sir B again. If, as Cheryl suggests, he was the target of Sir F's "drop", we know for sure that Sir F never got there. If Sir B did not tip off the LK about the drop, then all he presumably knows is that Sir F never showed up. And we can figure he wasn't waiting for Sir F in the comfort of his own keep south of the city, because Sir F was going the wrong way, as Dave has pointed out. Yet Sir B waited until dinner time the following evening to inquire at the Bridgetower. Now I'm sure that the sheriff is a busy man and all, but you would think he could have sent a man around with a message on the morning of the 11th to Sir F to the effect of "what the f***?", having been stood up the night before.
That, taken in combination with the excessive number of stakeouts detailed above, makes me partial to the notion that Sir B tipped off the LK. It gets rid of one of those stakeouts (ie somebody lurking near the inn waiting for something to happen), by making Sir B the arranger of things. I frankly continue to find it most parsimonious to suspect Sir B of having a hand in all three events (robbery, murder, ambush) because it radically simplifies things. But I nod to your scepticism.
And then there's the ambush. Quite honestly, I'm have a hard time making the obvious suspects fit. The methodology seems odd for Morgathians, but I confess to ignorance as to how they would go about things. My presumptions about them do not, however, involve them riding about on steeds, setting up military-style ambushes, and dueling with opponents with swords. And would they bother to dig shallow graves? The Agrikans seem more likely, except for the part about the graves perhaps, and Boraga's somewhat authoritative statement that the deed didn't bear their stamp. So I keep coming back to Sir B, in that the ambush seems more the work of the type of guys the sheriff would keep on hand. The corruption in the sheriff's department would, however, have to run pretty deep for his men to be complacent in bagging a Baron with impunity, so I would think Sir B would have needed to lead the raid himself, if he in fact was the instigator of it.
Come to think of it, Rahel has sufficient military muscle to ambush the Baron as well. Do we need to open a file on her as well?