Once one takes an interest and starts digging into the world of reggae it's amazing how deep the genre truly travels...certainly FAR past the 'upbeat reggae' that is typically more familiar. There are probably thousands of recordings that barely got out of the isles but, thanks to dedicated labor-of-love labels like Blood & Fire, Auralux, Pressure Sounds, Soul Jazz, etc., much of this music is seeing the light of day. The atmosphere and vibe that some of these vintage recordings conjure is, at times, pretty amazing. As for what you heard...? Hard to say. Typically, the 'scary' musical description would be attached to the deep, dubbed out 'dread' recordings. A lot of the early (though definitely not ballad-y) DJ stuff or some of the particularly subterranean Lee Perry recordings would fit this bill. Some of the dub oriented stuff that Horace Andy did or the Lee Perry produced Congos and Heptones records could fit your description as well. Don't know...could have been a number of things. If you feel so inclined, I'd suggest you start digging into the output of some of the labels I mentioned above and see what you come up with. The Soul Jazz 'Studio One' series of comps are highly recommended and could be a good starting point.