John Cardinal series 04 : By the time you read this

Detective John Cardinal of remote Algonquin Bay, Ontario is in mourning for his wife, an apparent suicide, when he starts receiving hate-filled notes gloating over his loss. Believing that his wife may have been murdered, he begins looking into who might be behind it. Meanwhile, his partner Lise Delorme is trying to track down the pedophile responsible for a cache of appalling photos featuring a possibly local girl.