Directorate of vigilance and anti-corruption (DVAC) sleuths have arrested a commercial tax officer (CTO) in Mylapore for taking a bribe of 15,000 from the owner of a pharmaceutical company on Tuesday.

Police said CTO assistant commissioner K Vijayaraghavan was caught red-handed while accepting cash from P Vaidyanathan, the owner of Orange Health Care Pharma, in his office in Mylapore.

"We nabbed him in the presence of two government officers who will be witnesses," a DVAC officer said. "We set a trap, applying the chemical phenolphthalein to the currency notes that Vaidyanathan was to hand over to the CTO. We searched his table and found the currency in a drawer."

Investigators lace currency notes with phenolphthalein to link a suspect to the money taken as bribe. The suspect is wiped down with a colourless solution of sodium carbonate and the areas that came into contact with the chemical turn pink.

Police said Vaidyanathan, who paid commercial tax online regularly for the past three years approached Vijayaraghavan to transfer his assessment files to his hometown of Sengottai. Vaidyanathan had recently moved out of the city and settled in his hometown and intended to run his business there.

"Vijayaraghavan demanded cash from him to transfer the documents," the DVAC officer said. "Vaidyanathan negotiated with him and finally agreed to pay him 15,000. Vaidyanathan approached us and we set a trap for the CTO."

Police also raided Vijayaraghavan's house in Mylapore. "We seized incriminating documents from his house. We have collected documents of fixed deposits and cash exceeding his known sources of income. We will check if he has any bank lockers," the officer said.