New Delhi: It has been three days since three serial blasts in the country’s financial capital sent shock waves across India. Investigations are on at several levels. Sources told CNN-IBN that there’s strong indication that TNT was used along with ammonium nitrate in the bomb that ripped Central and South Mumbai.

If confirmed, this means a highly skilled and known terror module would have been involved in the terror attack. Police have questioned several alleged SIMI members in Mumbai jails over the last 48 hours.

Rakesh Maria, the Maharashtra ATS chief on Saturday at a press conference claimed new leads and said a sketch of one of the suspects will be released soon. He said the ATS is scanning CCTV footage with the help of locals to identify faces on the visuals.

The Mumbai police have also ruled out suicide bombers in the serial blast that hit Mumbai. Maria said, “All angles including the underworld link are being examined.”

The explosives were kept in metallic containers at all the three blast sites and digital timers were used.

Sources told CNN-IBN that there could be a Kolkata link to the blasts and that the Maharashtra Anti Terror Squad (ATS) is in touch with the Kolkata Special Task Force (STF). This came after a suspect believed to be associated with the Indian Mujahideen (IM) went missing in the last few days.

Meanwhile a NIA team visited Ahmedabad on Friday to meet IM suspect Danish who was arrested by crime branch in connection with Ahmedabad blast of 2008. In Mumbai, people living close to a possible safe house of the terrorists are being questioned.

The Ahemdabad crime branch and Gujarat ATS is coordinating with Mumbai ATS with regards to information with IM modules.

In Mumbai, people living close to a possible safe house of the terrorists are being questioned as the police now believes that a safe house close to the blast locations was used as the assembly point.

Sources also said that the ATS has asked for the details of the passenger lists from Kolkata to Mumbai for eight days before the blasts. It has also asked for the reservation charts