King’s Dairy farmer Vadavasena Kulkarni died on Monday.
His body was brought to the state’s Capital, Chennai, where his mother and his son were brought for autopsy, the police said.
Mr Kulkanni, a former milkman, had been in the intensive care unit at Chennai Central Hospital since Sunday night.
His son, Ramesh, died of cardiac arrest.
He was 38 years old.
The police said Mr Kulkanna’s family had lodged a complaint against a neighbour for the death of the milkman.
A complaint has been lodged with the Chennai police.
In 2014, Mr Kolkanni was diagnosed with advanced prostate cancer.
He had undergone treatment in Hyderabad, Kolkata and Kolku and had returned to Tamil Nadu last month.