Dark Mirror by Barry Maitland

Protagonists: DCI David Brock and DI Kathy Kolla
Setting: London
Rating: 4.6

A beautiful graduate student, Marion Summers, suddenly suffers a seizure in the reading room of London Library, and dies. The cause: arsenic. While arsenic is no longer readily available, a few of the suspects do have access to it. Even stranger: Marion had been studying the pre-Raphaelite painters, who did use arsenic in their paints and for medicinal purposes.

Did Marion kill herself? Although it seems to be a suicide, Kathy Kolla thinks not, and she continues investigating the many suspects: Marion's research tutor, her stepfather, her lover and a strange stalker. This is a strong modern police procedural, but also a good British traditional story, with echoes of the Golden Age mysteries.

We also get strong characters in Brock, who has insecurities about his current relationship with Suzanne, who has a personal interest in the case, and in Kathy, as we watch her first tentative steps in a new relationship. This is the 10th book in the series, but the first I've read. There's enough backstory that I never felt lost.
I'm only wondering why it took me long to read a book in this series. If you like British traditional mysteries (and I love them), I highly recommend this book.