The 16-year-old boy confessed to the Juvenile Justice Board yesterday that he had killed the couple on July 7 and took away Rs 36,000, said Aizawl district SP C Laldina.
The boy was arrested from his home a day after the crime, Laldina said.
Laldina said quoting the boy as having told the Board members that he had been given a single-barrelled gun to hunt animals in the jungle surrounding his village and was overcome by the temptation to rob his step-sister so that he could buy a mobile phone.
The couple recently received Rs 66,000 from the government after being selected as the beneficiary of the state government's flagship programme - the New Land Use Policy of which they had already spent around Rs 30,000 and the rest stolen by the accused.
