Ghostly Awakening by E.M. Leya

As assistant medical examiner, Lance is used to seeing strange things, but when he suddenly starts seeing ghosts, he worries he’s losing his mind.
Angus grew up around the strange. With his mother able to see and speak to ghosts, he’s grown up knowing there are things most people can’t see or understand. When he accidentally catches Lance arguing with a ghost, he knows he has to step in before the man thinks he’s going crazy.
As Lance adjusts to his new ability, he also realizes seeing ghosts has its advantages. When several women are murdered in the area, it’s up to Lance and Angus to work with the ghosts of the victims to catch the killer.