Jorhat, March 3: Sivasagar police claimed to have solved the February 13 Sepon blast case with the arrest of an Ulfa (I) sympathiser today.

Two persons - Situ Agarwalla and Dimbeshwar Bhuyan - were killed in the explosion on February 13 morning at the residence of businessman and brick kiln owner Biren Agarwalla.

Situ was Biren's nephew while Bhuyan was one of his drivers.

Though the police had suspected Ulfa (I)'s involvement in the incident, they could not find the exact cause of the blast.

There were no clues regarding the type of explosive device used. No splinters or craters were found on the ground either.

Both the bodies were badly mutilated and there were no eyewitnesses either.

However, the police later found traces of potassium nitrate at the site.

Deputy inspector-general of police (eastern range) Satyen Gogoi told The Telegraph that the police arrested Bolin Barua, 40, from Borbum Nis Khalai Gurguru village under Moranhat police station in Sivasagar district.

Gogoi said Bolin, who is a 'die-hard' Ulfa sympathiser, has confessed to throwing a grenade at Agarwalla's house on the night of February 12, which incidentally did not go off.

'We presume the next morning one of the victims may have picked up the grenade. The other victim, who was close by, also bore the brunt of the explosion,' Gogoi said.

Sivasagar additional superintendent of police (headquarters) Jayanti Sarathi Bora told this correspondent that Bolin was not a trained Ulfa militant but was 'very deeply' associated with the outfit. After surrendering in 2008, he had been was arrested in 2010 for reportedly assisting Ulfa.

Bora said during interrogation, Bolin had reportedly said he was asked by a senior Ulfa leader to lob the grenade in a busy market area to create terror among the people so that the traders would comply with the outfit's extortion demands.

According to the additional superintendent of police, Bolin said he could not drop the grenade at the Sepon bazaar as there were lots of people that day and he did not want to get so many people killed, so he lobbed it at Agarwala's house which was nearby.

Bolin reportedly said the explosion there would serve the purpose.

Bora said Bolin has also confessed to planting the bomb on the eastern outskirts of Jorhat on the eve of Republic Day this year, which the police had detected just two to three hours before the celebrations.

Bora said police were on the lookout for two more accomplices of Bolin, with whom the group was carrying out subversive activities.

The Charaideo sub-divisional judicial court, where he was produced today, sent Bolin to police remand for seven days.