I'll nominate:
Faceless Killers by Henning Mankell
Henning Mankell is one of my favorite mystery/thriller authors, but I did not get around yet to reading this book. It is also one of the "1001 books".
Wikipedia:
Inside an almost isolated Skåne farmhouse in Lunnarp, an old man, Johannes Lovgren is tortured to death and his wife Maria savagely beaten and left for dead with a noose around her neck. Inspector Kurt Wallander, a forty-two-year-old Ystad police detective, and his team – Rydberg, an aging detective with a rheumatism; Martinsson, a 29-year-old rookie; Naslund, a thirty-year veteran; Svedberg, a balding, forty-something-year-old detective; Hansson; and Peters – are put on the case. Maria Lovgren is taken to a hospital, but dies anyway. Her last word: "foreign"
Rydberg has been examining the noose around Mrs Lovgren's neck and "has never seen one like it before". He thinks that Mrs Lovgren's last word is accurate, and that the murderers are foreign. But his conclusion leads to several racially-motivated attacks after the information is leaked to the press.
The story focuses on Sweden's liberal attitude regarding immigration, and explores themes of racism and national identity.
http://en.wikipedia.org/wiki/Faceless_Killers
Available at Amazon.