It's also annoying that some people keep being butthurt for half a decade and don't actually pay attention to facts.
I don't understand Michael Toennies. He acts like he owns everything and the artists were working for hire. While at the same time he has himself forked Crossfire and used free graphics, which was actually drawn for Nethack or came from Dink Smallwood.
I see, thank you for bringing this to our attention. It seems the beholder graphic was taken from Dungeon Craft, which doesn't seem to include it any longer (perhaps due to similar issues, I'm not sure).
Good to know. Unfortunately there is little exchange between upstream and downstream, so these kinds of copyright issues bugs may do a lot of damage, till everyone is aware. I had plans to use this beholder sprite in my Android strategy project, but by sheer luck decided to commission artist a better sprite, so they money weren't wasted improving SSI's property.
Are you aware of any other such problematic graphics?
Illithid/Mind Flayer (cthulhu like creature) sprite appears to be from SSI games. But don't trust me on that, check yourself or better yet ask people at FRUA forums if the sprite sheets contain sprites they recognize.
I've been in the process of replacing them with really free alternatives for a while, but the process for that isn't fast...
I've personally drawn a beholder sprite: http://opengameart.org/content/dread-oculus
You can use it if you wish, although it is somewhat worse than SSI's one or the beholder I've commissioned to the artist. There is a lot of isometric stuff on my OGA account.
And yes, a lot of the sound files are indeed of questionable origin
Daimonin's "Artistic Credits" file mentions http://www.futurewaveshaper.com/
as origin, which does give CC-BY license, although I'm unsure if they allowed to do that. Their site does look somewhat untrustworthy and quickly made. It is very common for various crooks to sell stuff they don't own, like the infamous allofmp3.com. Moreover, I'm unsure if all sounds come from http://www.futurewaveshaper.com/
Good luck solving this mess.