35-year-old RSS worker Rudresh was hacked to death by two motorcycle-borne men on Kamaraja Road on October 16, when he was with his friends after attending a Sangh event.
Police on October 27 had arrested four persons in connection with the incident.
They said that Sheriff's name was spilled by the four persons, who were arrested earlier, in the case.
PFI, a confederation of Muslim organizations, has condemned the arrest of Sheriff alleging that police have acted under pressure.
"The murder which took place because of local or personal reasons is being linked to the organisation," PFI General Secretary Yasir Hasan told reporters in Bengaluru.
Accusing BJP of "trying to mislead the police investigation", Hasan said, "Police without any reason are trying to fix our district President under pressure from BJP."
Noting that this was not the first time such baseless allegations were levelled against PFI, he said whenever the murder of any Sangh parivar member takes place in Karnataka, BJP or RSS blame the organisation without any investigation.
BJP, which staged protests over the incident, had blamed the "unholy nexus" of Jihadists and Marxists for the killing.
The saffron party had also alleged PFI's role in the murder.
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