The four were interrogated by police sleuths and produced during the day before Alipore Court, which remanded them to police custody till September 21.
Bodies of Gouri Bhattacharya(84) and her son Dipak(52) were discovered in a room in the first floor, while that of domestic help Anima Das(48) was found lying in the dining hall of ground floor and the attendant in the bathroom of the house on Biren Roy Road (West) on Thursday.
All the bodies had deep cuts on their throats and forensic experts had collected clues required for the investigation.