Kochi: Police on Monday registered the arrest of Dominic Martin, the prime accused in the multiple blasts that happened at a convention centre in Kalamassery here on Sunday. He has been charged under UAPA (Unlawful Activities Prevention Act), Explosive Substances Act, criminal conspiracy, attempt to murder and murder.

An extensive probe has been launched by state and central agencies to ensure there are no other links beyond Dominic Martin in the case. Police are even looking into Martin's life abroad to gather more information. Besides state police, the National Security Guard squad that landed in Kochi on Sunday inspected the blast site and collected evidence.

Though Martin has confessed to the crime and presented all evidence, the investigation teams have several hurdles to overcome before concluding he is the only suspect. The method chosen to commit the crime is what has intrigued the central agencies. IED (Improvised Explosive Device) blasting is a method commonly adopted by terrorist organisations. Hence, the probe teams will have to confirm there was no involvement of extremist organisations in the incident.

They are looking into aspects like whether Martin had any association with individuals affiliated with such organisations while abroad. His mobile phone, including his social media accounts, was subjected to detailed examination. His relatives and friends are also under surveillance. The chief minister himself clarified unless these aspects are thoroughly investigated, the case cannot be considered closed.

The investigation by central agencies, including NSG and NIA will be crucial in the case. With the help of advanced systems and equipment, the eight-member NSG team inspected the hall where the blast took place. Two specially trained dogs were also brought in during the procedure.

Those who attended the convention were permitted to take back their vehicles, which were impounded at the site, only after the central agencies combed the area. Further action will be taken in the case only after the central agencies reveal their findings.

The blasts were set off at a convention centre in Kalamassery near Kochi where a prayer meeting of the Jehovah's Witnesses -- a Christian religious group that originated in the US in the 19th century -- was held on Sunday. A few hours after that, Martin, who claimed to be an estranged member of Jehovah's Witnesses, surrendered before police in Thrissur district of the state, saying that he carried out the multiple blasts. 

Before he surrendered, he posted a video on social media stating his reasons for carrying out the blasts. By Sunday evening, a 21-member special investigation team (SIT) of the Kerala Police, headed by ADGP Ajith Kumar, was set up to probe the case. 

Initially, one woman had died and 60 were injured, six of them critically, in the blasts. Subsequently, one of the six critically wounded -- a 53-year-old woman -- succumbed to her injuries. By Monday morning, the death toll rose to three with the death of a 12-year-old girl who had suffered 95 per cent burns in the incident. 

Presently, 21 persons are under treatment for injuries suffered in the blasts and of them, 16 are in the ICU, a state Health Department bulletin said. Of the 16, three are in severely critical condition, it said.