Death penalty has got nothing to do with it. Source: Philippine Statistics Authority, various years.
This can only be explained by the breakdown of peace and order in the country, as the PNP under Purisima and Aquino lost control of the police, which likely were demoralized by the incompetence of the two. Aquino and his sidekick, Interior Secretary Mar Roxas, who was officially in charge of the PNP, were also unconcerned about the surge in crime.