I’m looking for a paperback book I read in the late 70s possibly the very earlier 80s. The book was non fiction, written about the murder of a woman’s teenage (she may have been in her early 20s) daughter. The mother solved the murder by receiving what she believed were messages from her dead daughter. The murderer was her daughter’s boyfriend (husband).
Just possibly Who Killed My Daughter? by Lois Duncan, though the murder was, so far as I know, unsolved.
Possibly the book by Lois Duncan, I think it’s called Who Killed My Daughter? though not all of your details fit.