Sullivan Donald H Sullivan 
Soul Hunters [EPUB ebook] 

Mark Rollins, Private Investigator, is shot and killed during a robbery. He finds himself on the "other side, " but it is nothing like he had ever imagined. To him, and others like him, it is extremely dangerous, for they must always be on the alert for The Soul Hunters. Mark searches for a way to resist the evil beings, but there is seemingly no way to stop them.