Bhupendra Vira had led a campaign against land mafia and encroachments in his Kalina colony, and recently complained to the police against a local strongman.
Activist and former Aam Aadmi Party leader Anjali Damania, who had worked with Mr Vira, alleged that he was targeted by those involved in illegal land dealings.
“The assailant entered Vira’s residence around 9 pm yesterday, put a gun to his temple and fired. He died on the spot,” said a police officer.
The police are investigating whether Mr Vira had complained about any threat to his life. Ms Damania alleges that he and several other activists had been threatened and they had also filed complaints.
Recently, Ms Damania said, Mr Vira had persuaded civic officials to issue four notices to a goon for illegal constructions.
The activist has three children, a daughter and two sons. One of the sons had allegedly been stabbed four years ago.
Mr Vira was attached to the ‘Voice of Kalina’, a citizen’s group.
He had written several letters to the civic body and the Lokayukta or anti-corruption watchdog, asking for action against illegal structures.
AAP has alleged that the land mafia had tried to usurp Mr Vira’s shop apart from several other properties in the area.