Unseen — Mari Jungstedt

The island of Gotland is in the middle of a busy tourist season and getting ready for Midsummer, the 4th of July of Swedish holidays, when a young woman and her dog are found brutally murdered. The dog has been beheaded and is missing a paw; the woman is naked, covered in gruesome axe wounds, and her panties have been stuffed in her mouth.
What looks like a crime committed by the victim's jealous husband keeps the local police force on their toes. Then a second victim is found. A serial killer terrorizes tourists and locals alike, and Inspector Anders Knutas has to face additional pressure from the media and local politicians who are worried about bad PR for the island.
In his quest for the murderer, he is aided by Johan Berg, an intrepid young journalist from Stockholm who has been sent to cover the incidents and who gets involved with Emma, one of the first victim's close friends. Three women die before Knutas and Berg, each approaching the case in their own way, finally close in on the killer, who has always, until now, been the one unseen by everybody.
Jungstedt has written an atmospheric and exciting first mystery in clear, unadorned prose, in the tradition of Henning Mankell, Håkan Nesser, and Karin Fossum.