The Jigsaw Man by Nadine Matheson

Imitation is the sincerest form of flattery...

When body parts are found on the banks of the River Thames in Deptford, DI Anjelica Henley is tasked with finding the killer. Eerie echoes of previous crimes lead Henley to question Peter Olivier, aka The Jigsaw Killer, who is currently serving a life sentence for a series of horrific murders.

When a severed head is delivered to Henley's home, she realises that the copycat is taking a personal interest in her and that the victims have not been chosen at random.

To catch the killer, Henley must confront her own demons - - and when Olivier escapes from prison, she finds herself up against not one serial killer, but two.