Mumbai police on Monday arrested four members of the Bhai Thakur gang for allegedly murdering tribal activist Navleen Kumar last month. Sanjay Kadu, Hazi Muthuswamy, Gajanan Patil and Chandrakant Rane were produced before a Thane court and remanded in police custody for eight days. Police said the names of the four accused have been appearing in cases of land-grabbing from tribals, a cause Kumar fought and died for.Kumar was a prime witness in the Suresh Dubey murder case in which Kadu, Patil and Bhai Thakur are the accused. Builder Dubey was killed on October 9, 1989 at Nallasopara railway station. Patil works for Thakur in the Vasai, Navghar and Manikpur areas.Kumar was murdered on June 19 on the terrace of her flat as she took a morning walk with her dogs. She was stabbed 19 times. Police said she had made enemies in her efforts to help tribals protect their land from the builders’ mafia.