A Mind to Murder by P. D. James

That a man who caught murderers should be a successful poet seemed inappropriate to some people. But Superintendent Adam Dalgliesh of the Criminal Investigation Department was attending his publisher's annual sherry party when a call from Scotland Yard whipped him away to investigate a particularly brutal murder. In the elegant Steen Psychiatric Clinic, which catered strictly for upper-class neuroses, sprawled the body of Enid Bolam, a chisel through her heart. It had been a vicious, calculated thrust, suggesting that the killer had not only confident knowledge of anatomy but unusual strength. But why, lying on Miss Bolam's chest, was there the grotesque wooden image which old Tippett, a chronic schizophrenic, had been carving in the art therapy department?