Whatever happened to Radaghast?

[Valandil]

My best guess is that if Radagast returned to Valinor, it was in spirit only - not aboard a ship.

Before the fellowship went out from Rivendell, scouts were sent in all different directions. I believe some went to Rhosgobel, looking for Radagast, but found no trace of him (found it - fourth page of "The Ring Goes South" in my edition). Radagast was a true 'home body' and was last observed headed for home - when he parted with Gandalf after giving him the message to go to Orthanc.

I suspect Saruman of 'foul play' - once Radagast had served his purpose of drawing in Gandalf. Or - at least after Gandalf escaped, suspecting him of direct aid, rather than indirect aid. Or even - questioning him and finding out enough to learn that Gandalf was able to contrive an escape through Radagast's arrangements. Or - there could have been a party waiting to get rid of him once he returned from running his errand, before Gandalf escaped anyway.

Then I think Saruman 'did him in'. He would have wanted no more of his interference.

(I wonder if Olmer suspects the Elven 'scouts' who were sent to Rhosgobel )