Back from the Deep by Doug Horner

The dramatic story of an unlikely search and recovery duo who help law enforcement and grieving families with their uncanny knack for locating bodies underwater
A powerful debut for fans of deeply reported stories that follow real people with obsessional passions, and of authors like Tracy Kidder, Sebastian Junger, and Patrick Radden Keefe
When the police and FBI exhaust their abilities and options, and when grieving families run out of resources, their last best hope has been an Idaho couple who have spent their retirement years pursuing lost causes - and have located 130 victims from lakes and rivers across the United States and Canada.
Gene and Sandy Ralston, a married Idaho couple in their mid 70s, are self-taught underwater search-and-recovery specialists who volunteer their time and equipment. And yet the Ralstons are counted among the best in the world. The Ralstons have an uncanny knack for finding bodies in deep water and can regularly find a missing person within hours, sometimes even minutes, of launching their boat.
Law enforcement and emergency response agencies seek out their peculiar expertise, but when the Ralstons' home phone rings it's usually a family member of a missing person. Someone reaching out after the local police and volunteer groups have called off the official search. Someone who heard from a friend of a friend about a couple from Idaho who will travel thousands of miles at the drop of a hat - charging only their travel costs - to help complete strangers.