Police identified the arrested as Umesh (38), Naveen (29) and Raghavendra (32), who were nabbed in Bangalore yesterday by a police team.
The arrested, who were produced before a local court, has been remanded in police custody for three days, police said.
RTI activist Vasudeva Adiga went missing on January seven and his body was found in a tank in Chikmagalur on January 13.
Adiga, also a Congress activist had unearthed several illegalities through RTI route, according to police.