Derek Blaikie Cornish, 85, died peacefully at home in Wichita, Kansas, on Sunday, April 20, 2025.  He was born in Walton-on-Thames, UK, just after World War II began in Europe.  He graduated from Kent College, Canterbury, University of Bristol, Goldsmiths College, and Reading University.  Prior to retiring and moving to Wichita in 2002, he was a senior lecturer at the London School of Economics.  He was a forensic psychologist (CPsychol FBPsS) and a co-developer (with Ronald Clarke) of the rational choice perspective in criminology.  He was proceeded in death by his father Lionel Cornish and his mother Christina Blaikie Cornish.  He is survived by his wife Martha Jane Smith, his son John Blaikie Cornish Sayers (Nighat Blaikie Noor) and the rest of the Sayers family (Tom, Marie Teresa, Freddie, Annamieka, and Saoirse), brothers-in-law James and David (Mary) Smith, sister-in-law Lucy (Clifford) Dorcy, nephews Alexander, Michael, Steven, and Kevin Smith, nieces Catherine (Ramsey) Gazal, Jennifer and Linda Smith, cousin Susan McKeag, and many good friends.  No funeral services are planned.  Ashes are to be taken to Edinburgh, Scotland, and Newton Abbot, Devon, to be near his parents' remains.  The family are grateful to the doctors, nurses, and other care professionals who helped look after him prior to his death.  Memorials to the Wichita Symphony Youth Orchestras Program, the University of Bristol, Department of Music  (https://www.bristol.ac.uk/alumni/donate/make-a-donation/usa/), or another department of music.