Speaking to reporters here, City Police Commissioner Chandrasekhar said Shenoy, charged with hatching the murder of Vinayak Baliga, had destroyed evidence.
The murder of the 51-year-old RTI activist on March 21 had rocked the district. All the suspects, except Shenoy, had already been arrested.
Baliga was hacked to death near his house at nearby Kodialbail on March 21 while he was about to go for a morning walk. Shenoy had been absconding since then.
The other five arrested are Vineet Poojary, Nishit Devadiga, Shivaprasad, and Shailesh and Manjunath Shenoy.
Manjunath is out on bail.
Police had filed a chargesheet in a local court on June 23 in which Naresh Shenoy was named as the first accused.
Baliga, an electrical contractor, had successfully sought out more than 90 RTIs, particularly helping the government in tracing electricity theft in the city.
He had also helped several poor families in the city, who were deprived of their rights. A bachelor, he had been living with his parents and three sisters.
PTI