This Professor only has a PhD degree
I know a few cases of researchers who don't have PhDs, but I've never seen this before.Probably the best known researcher in CS who doesn't hold a PhD is Simon Peyton Jones. He is very well known in the field of programming languages and one of the main implementors of the main Haskell implementation GHC. I think he might have started a PhD in the last few years, but he was appointed a professor at Glasgow without one.