The Raw version of what Kuroda said in the latest file(920) by jimmy_kud0_tv2 from DCTP
and here is the translated version by Spimer from DCTP
now i am not saying that he is RUM but i think the knowledge of conan being the brains behind "sleeping kogorou" came from Amuro.
cuz in file 897, he said "i'll explain everything to the higher-ups". and by that i think he is either an agent from the secret police or one of the higher-ups. though i don't know why he was in nagano first and then transfered to tokyo.
though above may not be the case and he might actually end up as rum given that gosho said that rum has already appeared.
and if that is the case then it would make sense why even after knowing he is the brains behind "sleeping kogorou" he won't be doing anything uh major(or something like that) until he founds out about conan-is-shinichi thing the same way Irish did in movie 13(or via some other method).
but he might be neither of what i said. with gosho being in hospital and all. all we can do is speculate and wait for the next file.