Ankit Saxena, a professional photographer, was killed on Thursday night in the area. The woman's family opposed her relationship with Saxena as the two belonged to different communities.
Four persons, including the brother of the woman, were nabbed a few hours after Saxena was stabbed to death by them.
"Three accused -- the mother, father and uncle of the woman -- have been sent to judicial custody. Her minor brother has been sent to juvenile home," a senior police officer said.
The woman claimed threat to her life and was sent to Nari Niketan. The family of the deceased has been given security, police said.
Local residents claimed the killing was not a fallout of Saxena being in an interfaith relationship.
A friend of Saxena said "news reports suggesting a communal angle in the incident are wrong".
Delhi BJP Manoj Tiwari who met the parents of the photographer said the incident should not be given a communal angle.
He demanded that Chief Minister Arvind Kejriwal break his "silence" over the killing and announce a compensation of Rs 1 crore for the family.
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