Linda Cajetan Andrade was found murdered in a naked condition at her residence at Velim village, 50 kms away from here, more than a month ago and the breakthrough in the murder mystery came yesterday.
Five people including two minor grandsons of the deceased and another minor boy were picked up from different locations in South Goa, after one of the accused confessed to the crime.
Superintendent of Police (South) Arvind Gawas said the gang was in need of the money to bet on IPL matches that were underway at that time and ongoing Euro Cup.
He said the murder was pre-planned as one of the grandsons invited his grandfather to his house in Navelim village to have a look at the 'love birds' which he had purchased from the market on the day.
Gawas said the only clue with the police was statement by a minor child from neighbourhood who had seen a boy wearing Carnival mask walking out of Linda's house on the fateful day.
Police zeroed in on the suspects after they were found frittering away the money, which they got by selling ornaments stolen from the victim's house. About Rs 4 lakh cash was also stolen after the murder.
Along with the three minor boys, police have also arrested Dattaraj Satoskar (21) and Alcin Mascarenhas (19) for masterminding the murder.