Police said they are probing whether the person Bharti had complained about is involved in the killings.
A woman who was gunned down with her husband and two young daughters - just one and six years old - at their home in Amethi on Thursday had filed a police complaint against a man less than two months ago in which she had said that he had threatened to kill her on more than one occasion and would be responsible if anything happened to her or her family.
Poonam Bharti, her husband Sunil Kumar and their two daughters were at their home in Amethi's Bhavani Nagar when a few men barged in and shot all of them.
Police said the crime seemed premeditated and did not appear to be a case of a robbery gone wrong. They also said Bharti had filed a case of sexual harassment, threat to life and offences under the SC/ST act against one Chandan Verma in August.
NDTV has now accessed the first information report (FIR) in which Bharti said that she had gone to a hospital in Rae Bareli on August 18 with her husband to get some medicines for one of her daughters when Chandan Verma misbehaved with her.
Bharti said that when she protested, Verma slapped her and her husband and also used casteist slurs.
"He said if you report this I will kill you. He has threatened to kill me before this as well. My family is in danger. If any incident or accident happens with me or my husband in the future, Chandan Verma will be responsible. I request you to register my report and take appropriate action," she had said.
Police have said they are investigating whether Verma is involved in shooting Bharti and her family and Uttar Pradesh Chief Minister Yogi Adityanath has promised strict action against the culprits.
The case is now being investigated by the UP Special Task Force (STF).
'At Least 5 Shots'
Ram Manohar Yadav, the owner of a medical store outside the house of Sunil Kumar, who was a teacher at a government school, said he heard at least five gunshots.
"I don't know how the attackers came. There is a way to enter the house from the back as well because parts of it are under construction. I did not see them coming from the front. Master sahab was a very simple person. They had been living here for two-three months," said Mr Yadav.
(With inputs from Arun Gupta)