Three members of a family, including an 8-year-old girl, were found hanging in their house in Alipurduar district on Thursday, police said.
Preliminary investigation revealed that 32-year-old Basudeb Pal strangulated his wife Anima, 25, and daughter Ankita, 8, to death with a gamcha (traditional cotton towel) and then hanged them, a senior police officer said.
Basudeb, stated to be a "habitual drunkard", later committed suicide by hanging at the house in Pakriguri village near the West Bengal-Assam border.
The office said the couple had a quarrel last night.
The bodies have been sent for post-mortem examination.
Basudeb used to work as daily labourer, the police said.
Local people said he used to work as a carpenter in Shillong and returned home only Wednesday.