The Mimic - M K Farrar - Bog

A copycat killer...A detective with a past...A prisoner who knows too much.
A killer who likes to replicate previous murderers' deadly deeds is stalking London's streets.
Detective Erica Swift had hoped to never see Nicholas Bailey-the man who killed her husband in front of her-again, but when he contacts her to say he's been corresponding with this new killer, she's forced to face him once more.