The Winter Kill. The Sir Law Kintour Mysteries, #2

Thieves and the unsavory of Perth: All in a day's work for lordless Sir Law Kentour.until a mysterious death in the midst of a Highland blizzard. When the sheriff of Perth demands that Sir Law show that the death was not an inconvenient murder, Law thinks this looks like an easy job. But circumstances seem to conspire against him, and another murder follows. Soon the King's chancellor becomes involved, making the mystery even more dangerous.
Not only does the murder investigation keep running into brick walls, his friend Cormac plunges into danger, and Law again encounters the thief who has already been a thorn in his side. When answers start to emerge, Sir Law gets more than he bargained for.