Murshidabad's Superintendent of Police Mukesh Kumar told media persons that Utpal Behera - a youth from Sahapur village under Sagardighi police station - was arrested on Monday night.
The bodies of primary school teacher Bandhuprakash Pal, his wife Beauty and their eight-year-old son Angan - were found in a pool of blood in their residence on Bijaya Dashami (October 8). The victims were hacked to death.
"Behera has confessed that he had committed the murders on Bijaya Dashami," said Mukesh.
On the reason for the gory crime, he said that Behera knew Pal, who taught at a school in Sahapur village and also worked as an insurance agent.
"Behera had given Rs 48,000 to Pal as premium for two insurance policies. But Pal gave him a receipt of only Rs 24,000. Despite several requests, Pal neither returned the rest of the money, nor did he give any receipt.
"Behera's father had met Pal a number of times at his school demanding either the receipt or the money, but he remained defiant. When Behera called up Pal, he misbehaved with him. Seething with rage after Pal hurled personal abuses, Behera decided to see to the end of the matter," said Mukesh.
Behera procured a sharp weapon and went to Pal's residence on October 8.
"As Pal turned after opening the door, Behera attacked him from behind him. With the victim lying in a pool of blood, Utpal went to the other room, and first murdered Beauty and then the child, both of whom knew him. It took him five minutes - between 12.06 p.m. and 12.11 p.m. - to commit the three murders," the SP said.
But Behera had to hurriedly flee when the local milkman went to the house finding the door ajar.
While searching the Pal's Jiaganj house, police got the clue about Behera's involvement from the blood-stained insurance papers in his name.
According to the police, Pal was associated with a number of insurance companies and used his position as a teacher to get people to buy policies.
The murders had caused a political storm, with the BJP and the Rashtriya Swayamsevak Sangh (RSS) claiming that Pal had been attending RSS weekly programme 'Milan' over the past few months. The BJP had called it a political crime and blamed the state's ruling Trinamool Congress for the deaths.
( With inputs from IANS )