The lie detection tests began on Saturday for the main accused and six others involved in the alleged rape and murder of a trainee doctor at RG Kar Medical College and Hospital.
The primary suspect, Sanjay Roy, will undergo a polygraph test in prison, where he is currently held.
The remaining six individuals—former principal Sandip Ghosh, four doctors on duty the night of the incident, and a civil volunteer—will take their tests at the agency's office.
A team of polygraph specialists from the Central Forensic Science Laboratory (CFSL) in Delhi has arrived in Kolkata to conduct lie detection tests on the suspects.
On Thursday, the CBI informed the Supreme Court that the local police attempted to cover up the crime.
According to the CBI, the crime scene was altered before the federal agency took over the investigation.
The rape and killing of the junior doctor in a seminar hall of the hospital has sparked widespread protests.
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. Roy was arrested the following day.
On August 13, the Calcutta High Court ordered the transfer of the probe from the Kolkata Police to the CBI, which started its investigation on August 14.
