NEW DELHI: Lie detection tests are currently being conducted on Sanjay Roy, the primary suspect in the alleged rape and murder of a trainee doctor from RG Kar Medical College, at Kolkata's Presidency Jail. Officials confirmed this development on Sunday. Additionally, two other individuals are set to undergo similar tests at the CBI office in Kolkata.

Four persons including former principal Sandip Ghosh underwent the polygraph test on Saturday, the officials said.

A team of polygraph specialists flown to Kolkata from the Central Forensic Science Laboratory (CFSL) in Delhi is conducting the tests, they said.

The CBI earlier told the Supreme Court that the crime scene was altered by the time it took over the probe suggesting there was an attempt by the local police to cover up the rape and killing of the post-graduate medic.

The medic's body with severe injury marks was found inside the seminar hall of the hospital's chest department in the morning of August 9. A civic volunteer of the Kolkata Police was arrested the following day.

The incident has sparked widespread protests.

The Calcutta High Court on August 13 ordered the transfer of the probe from the Kolkata Police to the CBI, which started its investigation on August 14.