
They suspect the killer may have sought to kill the whole family of four, as pesticide was also found in other milk, canned coffee and tobacco.
Police were looking into a land dispute between the victim's husband and a neighbour. However, they are also treating the husband as a suspect.
Juthamas Pattanasang, 34, a rubber farmer in Tambon Thung Kha Wat in Lamae district, died on her way to a hospital on Tuesday after drinking the contaminated milk.
Lamae superintendent, Colonel Phakhapol Thavishsri, yesterday said the insecticide had been put in the milk and coffee with a syringe.
Husband of the deceased, Samart Kongsung, 39, said the couple discovered the milk and coffee in their kitchen when they returned home after rubber tapping in the morning.
Samart said none of the family had bought the items and he told his wife not to touch them but she ignored him.
He said he gave some of the milk to a family dog, which collapsed about three minutes after consuming it.
The Nation
CHUMPHON