Mona Duggal (22), wife of the businessman's nephew Ajay, has been arrested, while her uncle Rajeev (25) - the mastermind of the case, brother Harjeet (22) and his friend Sanjay (34) are still at large, police said.
Mona and Ajay got married last year. However, the couple soon had a fallout and Mona started living with her mother in Sundarnagri. As the family's financial condition was not so good, they planned to rob Ajay's uncle Bajrang Lal Bokadia.
Bokadia, his driver Vinod Dubey (45), cook Bhola (30) and domestic help Anand Kumar (18) were found dead on Monday morning. Bokadia's hands and legs were tied to a chair, while his mouth was strapped and his throat slit. The three others were found lying on the floor with injury marks.
"No recovery has been made so far in the incident. It would be possible only after the three absconders are arrested," Yadav said.