Unusual detective story in that the killer is known and the P.I. is hired to provide evidence he is sane. Marsh Tanner was first hired to find the killer of Diane Usser, wife of a famed Berkeley law professor, by her parents. Tanner reluctantly agrees to poke around. He learns that Lawrence, Diane's husband, was famed for his brilliant use of the insanity defense to "get off" many supposedly psychotic killers.
Diane had been stabbed to death. She was naked and appeared to have been involved in some kind of tryst when she was killed. Lawrence found her dying. He was charged with her murder shortly after Tanner took the case, which seemed to be the end of it until Diane's mother shows up in his office. She says they had received a phone call from someone claiming to know that Lawrence was indeed the killer, but he intended to use his brilliant legal skills and knowledge of the insanity defense to get himself off. She wants Tanner to find evidence that Lawrence is *not* mad so that he'll be convicted and executed.
The more Tanner investigates the more peculiar he finds the case to be and when Usser insists he committed the crime and pleads guilty by reason of insanity, Tanner realizes he can't possibly have killed his wife even though he insists he had. Usser has his own reasons and one is really cute. "You accuse me of planning to manufacture the symptoms of mental illness, to prevail at my trial by feigning insanity. Well, did you know that since 1898 the impersonation of mental illness by a prisoner awaiting trial has been known as the Ganser Syndrome? And that some psychiatrists consider such an impersonation in and of itself as a manifestation of psychosis?"
Part of the appeal of Greenleaf, aside from the string resemblance to Ross MacDonald, is Tanner's sense of outrage and sixties quasi-radicalism. In a discussion with Usser about the economic disparity of the justice system, Tanner replies he's not sure it matters anymore. "I guess because outrage at economic disparity implies that all problems admit to economic solutions. We seem to be building a world where money is the measure of everything. Everything has a price tag; everything is measured by its financial aspect. I read the other day that a student decided not to go to medical school because it wouldn't be a good return on investment. That seems a little off the track."
I am reading all of Greenleaf's Tanner books. They are excellent.