MUMBAI, October 2: The police have arrested four gangsters, including a NSA detenue, for extorting money from businessmen in central Mumbai by impersonating as underworld don Arun Gawli's hitmen.``I have neither been to Dagdi Chawl nor do I know any member of the Gawli gang. I got the names DK and Bandya after reading newspapers,'' admitted Ramesh Bhagat, one of the accused. The accused told Express Newsline that they did not even know what DK stood for. One of them even said he did not know whether the names belonged to males or females.The case came to light when the four gangters threatened to kill a garage owner under the jurisdiction of N M Joshi Marg police station. They were demanding Rs 1 lakh as part of the fourth instalment in the last three months.Senior inspector Vijaykumar Kadam said the telephonic conversation made from ACE card 9820116180 was recorded. Analysis of the recordings and matching them with the police voice bank revealed that the caller were neither DK or Bandya, norwere they associated with Dagdi Chawls.Acting on the information, the police laid a trap at Worli on Thursday and the nabbed the gangsters red-handed as they about to accost the garage-owner to collect the ransom. They have been identified as Zamir Sheikh, Salim Mistry, Amar Sheikh and Ramesh Bhagat.The accused confessed that they had been threatening 21 businessmen simultenously for extortion. Grab whatever is being offered was the motto.Explaining the modus operandi, DCP Paraskar said the four men as many as 67 phone calls to 21 businessmen in the last 15 days. The accused have purchased SIM cards worth Rs 30,000 to carry out the extortions.Zamir, considered to be the mastermind in the case, is a NSA detenue and has been named in 25 cases, including murders. Bhagat incidentally is the nephew of `matka' king Kalyanji Bhagat.