The Blood Detective, by Dan Waddell

I enjoyed this book a lot, though the premise is a bit of a stretch. Nigel Barnes, a super genealogist, assists the police, DCI Grant Foster and DS Heather Jenkins, to solve a series of grisly murders through genealogical research. Waddell is pretty cutting about the sleazy ways genealogy can be turned to a profit. The budding relationship between Barnes and Jenkins is fun and the historic vignettes add an interesting dimension.