NEW DELHI, March 6: Even as the Delhi police is busy searching for Abdul Karim alias Tunda, who is believed to be the mastermind in the serial bomb blasts in and around the Capital since December 1997, they are just as desperately looking for a man called Aziz.A senior official says that Aziz's arrest is crucial because he had planted the three bombs which exploded at Kingsway Camp, Shakti Sthal and Chatta Rail on October 10 last year. While Tunda is reported to be in Bangladesh, Aziz is believed to be hiding in the city.Sources in Special Cell and the North district police say that they received this information from sources in Pakistan two months ago. Since then, several acquaintances of Aziz have been questioned, some even detained for days.But Aziz's suspected involvement in the October 10 incidents raises several questions as Delhi Police T R Kakkar had claimed on February 28 that the October 10 blasts had been solved, along with 15 other incidents, with the arrest of four youths on the previousday.Only seven bomb blast cases in Capital, including the Chandni Chowk blasts on November 30, the Punjabi Bagh blast on December 30 and the ITO blast on January 9 this year, were to be worked out, he had said.Kamran, Shakeel, Harun and Musa were picked up from different places on February 27. Their interrogation reportedly revealed that Kamran had planted 18 bombs in Delhi, including the ones which exploded on October 10.Sources say that Aziz' name had surfaced much before Kamran and others were arrested on February 27. His name had again come up during the latter's interrogation. So did his association with Tunda.Aziz hails from Calcutta and is believed to have crossed over from Bangladesh a few years ago. He came to Delhi early last year and since then had been working as an electrician. Sources say that his address was traced to a Seemapuri house, but when the police raided the place in January he was absconding. But the police reportedly discovered that Aziz frequented a mosque in the walledcity area. Fifteen days ago, the police picked up Zakir who works in the mosque and is suspected to be associated with Aziz.Zakir's relatives claim that he is still under detention. They also say that Zakir had no links with anyone matching Aziz's description.Sources say that Zakir has not been "arrested". Also, many others, including the the Imam in charge of the mosque, were reportedly questioned. Though most were summoned through Section 160 of Criminal Procedure Code, they are irked that they were questioned because Aziz might have offered prayers at the mosque on a couple of occasions.A senior Delhi police official says that detaining people for exacting information on suspects is nothings new. "Any information for nabbing the ISI backed agents behind the blasts is vital. And once in a while we have to resort to different tactics," he says.He adds that the Delhi police are also keeping a close watch on suspected Bangladeshis in the Capital after the February 27 arrests. Both Harun and Musahave been established as Bangladeshis who entered India five months ago. Aziz is suspected to have crossed over as well.