The Kerala government has sought a judicial probe into the alleged suicide of Confident Group chairman C.J. Roy during an income-tax raid at his Bengaluru office.

In a letter addressed to Union finance minister Nirmala Sitharaman, chief minister Pinarayi Vijayan alleged serious protocol-related lapses on the part of income-tax officials.

The family of Roy, who hailed from Thrissur in Kerala, have received from police a nine-page suicide note purportedly written by Roy and mentioning that he had been contemplating suicide because of business setbacks.

In a three-page letter to Sitharaman, Vijayan wrote that Roy's death was a "blot on the tax administration of the country" at a time the Centre's aim was "Non-intrusive Usage of Data to Guide and Enable (NUDGE)".

"It is quite surprising that the person on whose premises the IT department was conducting a search and seizure operation could proceed to lay hands on a loaded gun and shoot himself, when the tax department personnel were going ahead with search operations.

"The logical conclusion is that non-compliance with the... minimum essential protocol in the conduct of search has led to the loss of a human life. The central government should order a judicial inquiry into the incident and it will be in the fitness of things that the Commission of Inquiry be headed by a person who has had experience as a judge in a constitutional court," the chief minister wrote.

The purported suicide note attributed to Roy, 57, a technocrat turned builder, mentions that he had suffered setbacks related to foreign investments. He had apparently called his elder brother, C.J. Babu, a gold jewellery businessman in Phuket, and asked him to come down to Bengaluru.