After photos of prisoners accused of murdering a Kerala politician were posted on Facebook by one of them, Home Minister Thiruvanchoor Radhakrishnan visited the jail in Kozhikode, 300 km from the capital Thiruvanathapuram.
Seven prisoners accused of killing TP Chandrasekheran, who was a Left leader for the bulk of his political career, were uploaded on Facebook. The pictures were posted by an inmate accused of grafting the conspiracy that led to Mr Chadnrasekharan's gory death in 2012 - he was found cut into pieces.
In their pictures, the men are seen in jail, but not in prison uniforms.
"The Director General of police is probing the matter and action will be taken against those found to be wanting in their duty," the Home Minister said on Monday. A report on the lapses that allowed the prisoners to Facebook is expected to be given to him today.
The controversy erupted after local television channels reported on the social networking. They also said that one of the prisoners had easy access to a cell phone and was making hundreds of calls from jail.
Mr Chandrasekheran split with the Communist Party of India-Marxist in 2008 and founded the Revolutionary Marxist Party.
In 2012, he was cut into pieces in Kozhikode by a group of armed gangsters. 36 suspects are in jail for direct involvement or links to his murder. Among them are politicians with alleged links to the CPI(M), including the husband of a state legislator from the party.
Last month, a local channel showed TV visuals showed the law-maker, KK Lathika, eating with her husband at a restaurant while he was meant to be en route to hospital for a check-up.