I don't know what the PD stands for. She was English and wrote (writes?) British police procedurals. Her books are very well done, and she's highly thought of, but they're pretty dark.
Ruth Rendell and Minette Waters are younger English mystery writers; they write very dark stuff too.
I love the Elizabeth George books featuring Tommy Lynley and Company, though am not sure what I think about the last one in which tragedy struck one of the main characters...
The one book I read of hers was a disappointment. It was supposed to be a mystery, yet she brought in a brand new character near the end to be the murderer. That's cheating!