The accused - Savita Gupta (21), who worked as an assistant to the deceased, her 17-year-old brother, her boy friend Vinay Bose (24) and the latter's friend Gaurank Khawale (21) - were arrested on charges of murder-cum-robbery, police said.
Photographer and short-filmmaker Navraj Kwatra (65) was allegedly strangled to death at his residence on the ground floor in Wilderness Co-operative Society in Borivali last week on September 14.
His wife lives in Delhi, while daughter has gone to Thailand for some exhibition, police said.
According to police, Vinay was in need of money when Savita, who had been working as assistant to Kwatra for the past three months, told him that her boss was generous and always helped people.
However, instead of seeking help from Kwatra, Vinay along with his neighbour friend Gaurank, who works as a courier boy and also needed money for his bike repair, conspired to rob him.