Where to find official list of signers/fingerprints ?

[marks2]

I found and followed the instructions for verifying ISO images. BUT, there was no mention of where to find the fingerprints of the signers. So there's no way to "trust" the signatures, since anyone could have generated the sha256sum.gpg files and put their own signatures on the server. To complete the circle, one needs to know that the signers are official. I searched but could not find the fingerprints. Usually these are prominently posted some place so everyone can fill good about the verification results.

Thanks!
Mark