A 45-year-old woman allegedly poisoned her husband and teenage daughter before consuming it herself in a village here resulting in the death of all three family members, police said on Saturday.

All the three died in hospital, police said, adding that they have registered a case of murder based on the complaint made by the woman's father-in-law who alleged that she served food laced with poison to his 50-year-old son and grand-daughter before consuming some poisonous substance later.

The complainant alleged that his daughter-in-law was having an extra-marital affair with a man and this used to result in quarrels between his son and her.

Recently, the paramour again visited the home on June 9. When the woman's husband learnt about this, he tried to explain its implications and her 18-year-old daughter also tried to convince her mother that whatever she was doing was wrong, police said.

Later, a quarrel broke out between the couple over the issue and the woman allegedly even beat up her husband.

On Thursday evening, the woman allegedly mixed some poison in the dinner and served it to her husband and daughter. Later, she also consumed some poison, police said.

After some time, her father-in-law, who was away, reached home to found all the three in unconscious condition.

The complainant then called his younger son and other relatives who took them to the hospital where all the three died during treatment, police said.

Investigating Officer Jai Karan said on Saturday that a case of murder has been registered against the woman and her alleged paramour. Further investigations were under progress, he said.