 A new system of classification was then adopted in which inmates were grouped into 16 classes under three broad categories.On 1 January 1988, Tee Tua Ba took over as Director of Prisons, while Quek Shi Lei acted as an advisor to Singapore Prison Service and became CEO of the Singapore Corporation of Rehabilitative Enterprises (SCORE).When Tee Tua Ba was posted to the Singapore Police Force (SPF) as Commissioner of Police on 1 July 1992, Poh Geok Ek took over the Directorship of Singapore Prison Service until 1 November 1998.