Police today claimed that a Bihar MLA had masterminded the kidnapping of doctor Umesh Sinha and three persons were arrested from an abandoned house of the legislator. The arrests were made on May 6, while the doctor was released by the captors last night.The officer in-charge of Hazaribagh police station, Arvind Kumar, said the police have made the MLA, Rama Singh, the main accused after gathering ‘‘plenty of evidence including the use of his mobile by abductors during the 20 day captivity of the doctor’’. He said there was no separate FIR lodged against the MLA as the one lodged after the abduction would do.‘‘Persons picked up during investigation point to him (the MLA) as being the mastermind behind the abduction,’’ said DIG (CID) Pervaj Hayat, who led a Special Task Force (STF) to catch the abductors.Chief Minister Arjun Munda had asked DGP R.R. Prasad to constitute the STF after nearly 2,000 doctors struck work. Sinha, who is in charge of the block health centre at Bishnugargh in Hazaribagh district, was kidnapped on his way to Ranchi on April 17. Hayat said the STF traced the kidnappers after they made a call to the doctor’s house, using a mobile in Patna, to demand a ransom of Rs 50 lakh. The team found out that the doctor had been kept at Jamdaha in Bihar. Rama Singh had won the last Assembly elections from Manhar in Bihar. He has two houses in Patna, one in Rajiv Nagar and the other at Bailey Road, from where the three persons — Manoj Singh (Aurangabad), Manoj Singh and Surendra Rai — were arrested. Hayat said one Gopal Prasad, charged with the abduction of Dhanbad businessman Naresh Agrawal, confessed that he was the MLA’s employee. Manoj Singh has also admitted that he was on Rama Singh’s payroll. Asked whether the MLA will be arrested, Hayat said: ‘‘We have clinching evidence against all the accused. We will move the court seeking its directive to proceed ahead in this case.’’