CBI officers on Sunday conducted a lie-detection test on the main accused, Sanjay Roy, in connection with their ongoing probe into the rape and murder of a woman doctor of state-run RG Kar Medical College at Kolkata's Presidency Jail where he is currently lodged, an officer said.

The CBI also searched various places in connection with its probe into the alleged financial irregularities in the hospital.

The central agency officers also conducted polygraph tests on a couple of others at their Kolkata office, he said, adding that the test on Roy was over after around four hours.

Four persons including former principal of the RGKMCH Sandip Ghosh underwent the polygraph test on Saturday.

The CBI has sought permission from a local court in Kolkata to put seven persons including Roy and former principal of the RGKMCH through the lie-detector test. The test cannot be used as evidence during the trial but findings give the agency a direction for the further probe.

A team of polygraph specialists flown to Kolkata from the Central Forensic Science Laboratory (CFSL) in Delhi conducted the tests.

A civic volunteer of the Kolkata Police, Roy (33) was arrested by the Kolkata Police on August 10, a day after the body of the 31-year-old medic was found in the seminar hall of the medical college.

A Bluetooth device found near the medic's body led to Roy's arrest. CCTV footage also showed him on the third floor of the hospital where the seminar hall is situated.

The accused allegedly was close to a few senior Kolkata Police officers, following which he was moved to the Welfare Board of the force.

The CBI earlier told the Supreme Court that the crime scene was altered by the time it took over the probe which suggests 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 on August 9 morning, sparking widespread protests.

The Calcutta High Court on August 13 ordered the transfer of the probe from the Kolkata Police to the CBI.

Meanwhile, CBI sleuths launched simultaneous search operations on the premises of Ghosh, ex-medical superintendent and vice principal of the RGKMCH Sanjay Vashisth and 13 others in and around Kolkata in connection with their probe into alleged financial irregularities at the institute, officials said.

CBI also searched the residences and offices of those engaged in supplying materials for the management and care of patients.

At least seven officers of the central probe agency questioned Ghosh at his residence from 8 AM till 7 PM while other officers were grilling Vashisth and another professor of the forensic-medicine department of the medical establishment, among others, they said.

The CBI team, which reached Ghosh's residence around 6 am, was made to wait for nearly one-and-half hours before he opened the doors, the officials said.

The other officers of the central agency went to the residence of a couple of suppliers in two areas of Kolkata and another in Howrah.

They also summoned the present principal Manas Kumar Bandyopadhyay and asked him to accompany them during the investigation inside the hospital - the ex-principal's office in the hospital and the canteen in the academic building.

Later in the evening, the CBI sleuths took Vashisth and his family members to his second residence in the city and started searching.

Till the last information shared by the CBI officers, the professor of the forensic medicine department, who was called to the CBI office, is being questioned, the officer said.

According to the complaint lodged by former deputy super of the RGKMCH Akhtar Ali, Ghosh during his tenure as the principal of the RGKMCH along with his associates, issued tenders for the construction of food stalls, cafes, canteens and urinals without the permission of the health department and the College Council.

Initial probe revealed that three special traders got each of these "illegal" tenders, a CBI officer told PTI.

Meanwhile, the agitating junior doctors at the RGKMCH said that they would continue their cease work unless the deceased doctor gets justice and the Kolkata Police Commissioner Vineet Goyal resigns from his chair.

Sunday was the 17th consecutive day that the junior doctors have been on cease work badly affecting healthcare services in Bengal.

The gruesome crime resulted in nationwide protests by doctors and citizens.

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