The Special Cell of the Delhi Police has picked up four persons,including a city-based trade union leader and his wife,for alleged links with Maoists. The four have been identified as Gopal Mishra,43; his wife Anu,38; one Pradeep,and a fourth person whom the police have not named. While Mishra was arrested,the others were picked up for questioning,sources said. According to sources,Bihar and Jharkhand police officials will arrive in the Capital soon to interrogate the four. This comes days after another suspected Maoist operative,identified as Ajay Singh,was arrested on April 23. Singh was allegedly involved in several operations in Bihar,including the incident in which a police jeep was torched during the Bihar bandh on March 23. According to sources in the Special Cell,Mishra has been slapped with charges under the Unlawful Activities (Prevention) Act. A source said: He was arrested from Shahdara on Sunday evening. We produced him in a city court on Monday and got his police custody. The police then took Mishra to his house in East Delhis Ram Nagar and picked up his wife,Anu,when she returned home on Monday evening,the source said. Pradeep,also a trade unionist,and the fourth suspect were picked up for alleged links with Maoists. According to the source,the Special Cell zeroed in on the four after investigations found Maoist infiltration in some trade unions in the city. According to the source,there is an active trade union in Okhla Industrial Area of South Delhi that is heavily influenced by the ultra-Left ideology of Maoists. The union reportedly targets displaced labourers,according to the source. Mishra,the source said,is a full-time leader of this union and brings out a Hindi newspaper called Mazdoor Morcha. Meanwhile,an NGO called Committee for the Release of Political Prisoners sought the unconditional release of the trade union activists and Anu (Mishra). In a statement,the NGO also said the four should be given access to lawyers. We have sent a letter to the National Human Rights Commission seeking its intervention to get them released, it said. We demand that he (Mishra) be given access to a lawyer and (police should) not violate his right to silence through intimidation and torture. Earlier,on April 4,the police had detained Sunil Mandiwal,an assistant professor at Delhi Universitys Dayal Singh College,for suspected links with Maoists,including arrested leader Kobad Ghandy. He was released following questioning. Another suspect Maoist Ajay Singh,arrested on April 23,was later sent to Bihar polices custody.