The decomposed bodies of a 35-year-old online trader, his wife and minor son and daughter were found on Saturday in a house in Taloja area of Navi Mumbai, police said.
The bodies of Nitesh Upadhyay, his wife Babli (30) and his eight-year-old daughter and seven-year-old son were found in Shiv Corner building in Taloja's sector 9 by flat owner Rajendra Bharadwaj who had come to collect rent, an official said.
When Mr Bharadwaj did not receive a response after knocking at the door, he went to the chairman of the housing society and opened the flat with duplicate keys, he added.
"Nitesh was found hanging from the ceiling fan while the other three appear to have been strangled to death. A suicide note found at the spot said that ''gold and cash were kept in the bedroom''. It also had a request that the cremation be done as per Hindu customs," the official said.
"We have registered a murder case against Nitesh, as we think he strangled the others to death before ending his life, and are probing for more details into the incident," he said.
The Taloja police station official said Nitesh's family has been contacted in Delhi.