What do you know about criminal cases?

Now consider a family. Him father is a prick and he must die. Otherwise, the children and the mother will die. Because the house they live in is unsafe. The father is always threatening and there is violence at home. They have 2 girls and 1 boy. The boy is the youngest 14 years old. The elder 17 and the middle 16. The middle child comes to the decision to kill the father. When he comes back from work on Saturday evening, he puts 7 sleeping pills in his drink and the father sleeps. At night, while he is sleeping, she turns on the gas stove in the room so that she is poisoned and passed out. It's 01:00am at night. It does not turn off the gas until 07:00am o'clock. And he is careful that there is no explosion in the house. Then he injects potassium xchloride into his body to make sure he dies.
I think it was very quiet and clean. People say that his heart stopped and he died.

How do you think? Any chance of my dad waking up here when he was gas poisoned?
or any other alternative ideas.
What do you know about criminal cases?
5 Opinion