The man, a junior accounts officer of the BSNL customer care service centre, Thiruvananthapuram, was included in the list of accused, they said.
Earlier, police had served a notice on BSNL to ascertain if the call details of Deputy Superintendent of Police Josy Cherian had been accessed by unauthorised persons.
Police had registered a case against the BSNL employee and also CPI(M) mouthpiece 'Deshabhimani' newspaper under the Information Technology Act after details of the calls by Cherian appeared in the paper.
On July 10, the newspaper reported that Cherian had allegedly given information related to the probe to mediapersons.
Chandrasekharan, a former CPI-M leader from the party stronghold of Onchiyam in Kozhikode district, was killed at Vallikkad near Vatakara on May 4.
He was expelled a few years ago after falling out with the CPI-M leadership and later floated the Revolutionary Marxist Party (RMP).
Several CPI(M) workers have been arrested in connection with the case.
