NEW DELHI, June 2 -- "Zaildar Estate Private Road. Trespassers will be prosecuted," reads a black signboard at the entrance of the street in Saidulajab where a building collapse killed six people on Saturday evening. According to police, the so-called "estate" is owned by three brothers including 71-year-old Karamveer Zaildar, who was arrested by Delhi Police on Monday.

Zaildar, a resident of Church Road in Vasant Kunj, was nabbed after a nearly 48-hour search in connection with the collapse of the building, where two additional floors were allegedly being constructed atop an existing four-storey structure.

Investigators privy with the case details, who asked not to be identified, said local residents had immediately identified Zaildar ...