Ho Xuan Hai, 53, had tried to kill himself along with them after piling up debts through a failed business venture.
He had invested all his money in a pig farm in Khanh Hoa’s Cam Lam District but it failed, and he was in no position to repay his debts.
In desperation, he wanted to kill himself and his entire family.
On Aug. 22, 2023, he searched online for ways to carry out the suicide-murders and bought a 40-liter cylinder of carbon monoxide (CO) gas.
At around 2 a.m. the next day, when his wife, 49, and three daughters aged 11-22 were sleeping in a room with air-conditioning, he released the gas into the room and stayed there with them.
It took until noon that day for relatives to discover them. By then Hai’s wife and children had died and he was in critical condition.
He was taken to a hospital and saved.
CO has no odor or color and is very difficult to detect. When someone inhales it, the gas quickly penetrates the blood and reduces oxygen levels, causing headaches, dizziness, nausea, chest pain, and confusion.
People who inhale large volumes can pass out and die very quickly, especially pregnant women, young children and seniors with chronic heart or lung diseases.