Bengaluru: The Congress's Karnataka unit on Wednesday sought an impartial and fair investigation into the death of Coffee Day Enterprises founder V G Siddhartha, saying "the invisible hands that ended his life" should be uncovered.

The party said the matter "is very unfortunate". Former Karnataka Chief Minister and senior Congress leader Siddaramaiah said Siddhartha's death was "both disturbing and mysterious". "The reasons and the invisible hands that ended his life in this tragic way should be unearthed through impartial and fair investigation," he said.

"Result of harassment by IT officials & decline of India's entrepreneurial position turning virulent by the day, with Tax Terror & collapse of economy. Companies which flourished under UPA have been shut down with many people being jobless (sic)," the state unit posted in its official handle.

The Congress was referring to the letter purportedly written by Siddhartha, the son-in-law of former Karnataka Chief Minister and BJP leader S M Krishna, alleging harassment by the Income Tax Department, which has denied the charges.

Siddaramaiah said the letter supposed to have been written by Siddhartha talked about "tax terrorism", which is the "ugly face of politically motivated institutions". "What signals are we sending to budding entrepreneurs without even an attempt to reform?" he asked.

Congress spokesperson Brijesh Kalappa said, "He was killed mercilessly by tax terrorists who are now seeking to besmirch his memory by selectively leaking material against him."

The body of Siddhartha, who went missing on Monday, was found on the banks of Nethravathi river near the coastal city of Mangaluru on Wednesday, with the investigation so far pointing to suicide.