A 35-year-old doctor allegedly killed his wife, her parents and their five-month-old daughter before committing suicide at his house on Sunday, police said.
The macabre sequence of events unfolded in New Palasia area, where Rohit Dwivedi hacked to death his wife Priyanka (30), her father GP Pandey (62), and her mother Gayatri (55), Additional Superintendent of Police Ramji Shrivastava said.
Later, he strangulated his infant daughter Sushi, and then hanged himself to death, Mr Shrivastava said.
Police recovered a blood-stained surgical knife from the flat.
A 15-page letter was also recovered from the spot, in which Mr Dwivedi mentioned his strained relations with his wife, the ASP said.
Further probe is on into the case.