The series of blasts on October 30 at four places in Assam, including Guwahati will now be investigated by the CBI The state government had set up a Special Investigation Team (SIT), led by an inspector general of police (IGP), to investigate the serial explosions, but despite 11 arrests, the SIT was unable to make any headway in the case. The decision to handover the investigation into the serial blasts and the ethnic violence, to the CBI was taken after an all-party meeting convened by the state Chief Minister Tarun Gogoi.

The CBI would also take over the investigation into the ethnic flare-up that left 58 dead and over two lakh homeless in Udalguri and Darrang districts of the state earlier in the same month. There were allegations that a section of miscreants had hoisted the Pakistani flag at a certain place in Udalguri district during the ethnic violence between the immigrant Muslim settlers and Bodo tribe community.

The SIT investigation had confirmed the involvement of the banned National Democratic Front of Bodoland (NDFB) and the United Liberation Front of Asom (ULFA) in the serial blasts that were plotted and remote-controlled by a third force sitting outside the country. The needle of suspicion is pointed at Harkat-ul-Jehadi Islami (HuJI) of Bangladesh.  

This is the second time the CBI will be investigating a bomb blast in Assam. It had earlier investigated the death of Nagen Sharma, the minister of Forest and PWD, and others, in a bomb blast in 2001.