Joukkomurha is not very well known within "noise scene", I would say, but it hold absolutely crucial role for some of folks of my age. One mandatory thing is, that he published COSMONAUTS HAIL SATAN tape, that included songs from two first demo tapes, with new cover illustrated by S.A.Hynninen, who later one became sort of infamous underground music character. When guys like myself, and just about everybody I knew, got this tape, it was mindblowing.
Cosmonauts Hail Satan, mysterious, but I suspect some know who they are. Mr. Satan died years ago. He did write on this forum. Mr. Cosmonaut, is alive and still doing things. If something would need to be reissued, I feel CHS is among those! All the 7"s, the early works in complete. Man, that would fucking rule!
Joukkomurha all in all, he was putting out zines that would have element of DIY punk, art, poetry, weirdness. Just the old school underground in the ways that I dont think happens anymore. Heloy Käet & sons was the name of zine since the 80's. Tapes, most of them I believe are ultra limited. Not "editions", but dubbed on demand - which tend to be near non-existent. So despite being well known figure, I doubt most people these days remember him.