[3] After the Japanese occupation of Manila in 1942 during World War II, Karingal stayed behind enemy lines to engage in espionage and sabotage missions for the Allies as part of President Quezon's Own Guerrillas.

[3] After the war, Karingal was sent to the United States for advanced training, spending three months at the Provost Marshal School in Fort Sam Houston in San Antonio, Texas.

[3] In 1967, President Ferdinand Marcos appointed Karingal to head the Philippine Constabulary Metropolitan Command's Northern Police District, which included Quezon City.

After Marcos declared martial law in 1972, Karingal became known as one of the most feared military commanders of the dictatorship, gaining a reputation for violently suppressing antigovernment demonstrations.

[5] In January 1984, he deployed riot squads armed with automatic rifles, gas guns and batons to crush a protest march against the Aquino assassination.

[6] On May 24, 1984, Karingal, by then a brigadier general, was shot and killed by two gunmen while dining with fellow police officers at the Fisher's Reef Restaurant[3] along Scout Borromeo Street[2] in Barangay South Triangle, Quezon City.