Four sticks of C4 plastic explosive were found in one house, and four bags of urea fertiliser, the main ingredient in the car bomb which killed six people and wounded a dozen in nearby Sungai Kolok on Thursday, were found in the other, he said.
A younger brother, later taken for questioning by the army along with his mother, said the explosives and fertiliser belonged to his older brother, said Tani, the deputy commander of police in the south.
"We've been keeping a close eye on him for more than a week" because he was a former communist who had a reputation as a bomb maker, he said.