The deceased, Sujith (28), who was attached to the armed reserve camp here, was found with a gunshot wound on the head at his home at Kadakal in Kollam district, they said adding he had also cut veins in both hands.
Though the officer was rushed to the hospital, his life could not be saved.
Sujith, a bachelor, has left a suicide note, police said. Meanwhile, the Minister's office said Sujith has been working as Thomas' personal security officer for the past three months and was on leave yesterday.
(With inputs from agencies.)