CBI sources said Baburao R Ramanna and Umesh Shankhe, who both accused in other murder cases as well, were arrested for allegedly hatching conspiracy to kill Mr Jha.
CBI has arrested two persons in Mumbai in connection with the 2012 murder of Right to Information (RTI) activist Premkant Jha, who was seeking information about the multi- crore illegal construction industry in the cosmopolitan city.
CBI sources said Baburao R Ramanna and Umesh Shankhe, who both accused in other murder cases as well, were arrested for allegedly hatching conspiracy to kill Mr Jha by hiring contract killers as he had sought information about their illegal constructions on which action was initiated by a local body.
Mr Jha, who was on his bike, was allegedly shot dead by the killers hired by the duo on February 24, 2012 with bullet piercing below his helmet, the sources said, adding the local police had also recovered an empty shell from the spot.
The duo have been sent to police custody till January 18 by the chief judicial magistrate of Vasai, the sources said.
The activist was part of an NGO "Brashtachar va Atyachar Virodhi Samiti' and had filed numerous RTI applications and complaints against illegal constructions in the Vasai-Virar area of Mumbai, they said.
The sources said it has been alleged that Mr Jha was extracting money and other considerations from the builders engaged in illegal constructions, which led to the enmity with various other businessmen.
They said Mr Jha had allegedly filed some RTI applications with regards to constructions in which Ramanna had interests following which action was taken. Ramanna and Shankhe, who were both in Thane Jail, in connection with a different murder allegedly hatched a conspiracy when they were on bail to get Mr Jha eliminated.
The sources said the duo hired some contract killers who were allegedly co-accused with them in a different murder case. They said the contract killers were yet to be arrested by the agency which has taken over probe in the case in October, 2014 on the order of the Bombay High Court.