Looking at a regular Dr. Kevorkian here. Except in this case, the Dr. Death was Eldon Mate and he was found brutally murdered in his own "death van". Alex Delaware is a psychologist who sometimes (as in 14 books, sometimes) assists his Homicide Detective friend, Milo Sturgis, on cases.
Sturgis calls in Delaware to the scene and they meet the couple of hikers who discovered the body. It's a gruesome one and one where a considerable amount of people are happy Mate is dead, while others are sad that their confederate in assisted suicide was murdered. Very odd split of people. Delaware's first thought was to Richard Doss, a man whose daughter he counseled after her mother was "assisted" to death by Mate previously. Doss, a wealthy asshole, already has an alibi (well, isn't THAT suspicious?) but wants Delaware to see his daughter again to counsel her on college choices.
Things just start getting messy and complicated, with more and more characters filing into the scene, all with ample motive to want Mate dead. The story got interesting as you tried to sort everyone out and discard who couldn't possibly have performed such a murder.
And then, near the end, you are walloped in the face clear from left field. Thanks to this, I ended up with a book hangover this morning because I had to stay up, damn the time!, and finish.
Good job, Mr. Kellerman.