The CBI officer supervising the investigation of the Tapasi Malik rape-and-murder case of Singur was today booked on charges of extortion and amassing wealth disproportionate to his income.

CBI SP A K Sahay was overseeing investigation of the alleged rape and murder of Tapasi, a member of the Save Farmland Committee protesting against land acquisition for the Tata Motors small-car project. Sahay’s team had named Debu Malik, a worker of the ruling CPM, as the prime accused, and also arrested CPM’s Singur zonal committee secretary Suhrid Datta.

Sources said complaints against Sahay — he was to retire next month — had been lodged with the CBI director and the Chief Vigilance Commissioner. One of the complaints was in the form of an affidavit.

A 12-member CBI team knocked on Sahay’s new flat in Beliaghata, Kolkata, and searched for over 12 hours. His office in Salt Lake and his house in Dhanbad were also raided. In one case, the CBI claimed, an NCB officer allegedly paid Sahay several lakhs of rupees in August 2005 at a hotel in Shakespeare Sarani to be let off the hook. The money was later transferred to Sahay’s account.