Books like The Vanished Ones

We call them the sleepers...At the elite Missing Persons bureau of the Federal Police, Mila Vasquez is tasked with finding the hundreds of lost people who have vanished from their former lives. However, the longer they are gone, they more they are forgotten by the world. Now they are returning. Appearing at random, wielding devastation and heartbreak, they enact a horrifying pattern of murders, leaving Mila scrabbling to discover where they have come from and they want before it's too late. Yet the deeper into the case she gets, the more Mila begins to realise that her colleagues are hiding something from her - something which will jeopardise everything...