Well, first, how there could be that many murders in Gotland, but never mind. What confuses me is what exactly was made. According to IMDb, we got a four part series in 2008, and four separate episodes in 2010 (plus the feature movie in 2012). I have four English subtitle files for the 2008 series, but not the vids, and I've watched six episodes from 2010, not four (five of the English sub files needed to be re-synched). I have the movie vid, but there are no English subs (yet).
As far as the show goes, well, nothing special. The Maria Wern character is a pretty ordinary cop, she seems to have no special gifts, no unusual personality quirks. Aside from the actress being pleasant to watch, I don't really get why this needed to be made. I enjoyed it well enough, but am I jonesing over the 2008 and 2012 material I haven't seen? Not really.