When reports of the gutka scam in Tamil Nadu first emerged last year, it stirred a debate about corruption in the higher levels of the state government and police. The scam grabbed the headlines again last week, when the Central Bureau of Investigation on September 5 conducted raids at 35 locations in Tamil Nadu and Puducherry. Among its targets were the home of Health Minister C Vijaya Bhaskar and Director General of Police TK Rajendran.

It arrested five people, including AV Madhava Rao, one of the promoters and directors of Annamalai Industries, which manufactures the MDM brand of gutka, a mixture of chewing tobacco, betel nut and palm nut.

The Opposition is using the scam to attack the ruling All India Anna Dravida Munnetra Kazhagam government, which has seen a series of crises following the death of its leader and former Chief Minister J Jayalalithaa in December 2016. Here’s a rundown on what the scam is about.

What is the gukta scam?

Gutka was banned in Tamil Nadu in 2013 for being among the causes of oral cancer. Investigators have alleged that the promoters of Annamalai Industries, formerly known as Jayam Industries, paid crores of rupees in bribes to high-ranking ministers, senior central and state government employees and police officials to allow the company to continue to manufacture and sell MDM gutka in the state despite the ban.

It has been alleged that Jayam Industries was renamed Annamalai Industries to allow the banned product to continue to be made and sold in the state.

The scam first emerged in July 2017 when income tax officials raided the premises of Annamalai Industries, which had been accused of evading taxes worth Rs 250 crore.

Who has been arrested so far?

After the September 5 raids, the Central Bureau of Investigation arrested AV Madhava Rao, Uma Shankar Gupta and PV Srinivasa Rao, promoters and directors Annamalai/Jayam Industries. It also arrested P Senthil Murugan, an official from Tamil Nadu’s Food Safety and Drug Administration department, and K Pandian, Superintendent of the Central Excise Department.

Why is the CBI involved?

During the income tax department raids on Annamalai Industries in 2017, officials seized two diaries containing the names of the people who were allegedly paid bribes by the gutka manufacturers. These diaries contained details of monthly payments of up to Rs 39.91 crore made over two years (2014-2016) allegedly to the health minister, two former Chennai police commissioners, and other officials. The Income Tax Department had sent a confidential report to then Tamil Nadu Chief Secretary PS Rama Mohana Rao but no action was taken.

In Arpil, the Opposition Dravida Munnetra Kazhagam filed a petition before the Madras High Court seeking that the CBI be asked to take over the investigation because of the alleged involvement of senior ministers, police officials, and state and central government officials in the scam. The Madras High Court ordered an inquiry by the CBI. This order was later upheld by the Supreme Court. In this case, a First Information Report was filed in May against unidentified officials of the Tamil Nadu government, Central Excise Department and Food Safety Department.