Double bass in death metal

Michael Kaplan asked me a few years ago who had first introduced double-bass speed drumming into death metal.

Here's what I would guess is a reasonable lineage:
Jazz drummers were almost certainly the first to use double-bass set-ups at all. Some late 1960s rock drummers also used it, mainly in drum solos.
On Deep Purple's 1971 album Fireball, on the title track, there is a reasonably fast double-bass beat used throughout the song. This isn't near death metal speed, but is a slower version of the same concept. (Fireball )
On West Bruce and Laing's self titled album from 1973 , the track Love Is Worth The Blues features some double bass towards the end of the guitar solo - quite a bit faster than Ian Paice's beat on Fireball.
Judas Priest's Sin After Sin (1977), particularly the track Let Us Prey, may feature the first double bass beat in 'pure' heavy metal song. (Let Us Prey )
The earliest (and very influential) 'real' death metal style drumming I can come up with is the work of Dave Lombardo of Slayer. 1984's Haunting The Chapel may be a good example of this. (Haunting The Chapel )

As always, I could have missed something!