Kolkata/IBNS: The Central Bureau of Investigation has named arrested civic volunteer Sanjoy Roy in the first chargesheet which was on Monday filed in the case pertaining to the rape and murder of a 31-year-old trainee doctor at Kolkata's RG Kar Medical College and Hospital.

Sanjoy, who was arrested by the Kolkata Police before CBI took over the case, has been named as the rapist and murderer of the doctor.

However, the probe agency is investigating whether there was more involved in the crime, which took place on the intervening night of August 8 and 9.

The accused had committed the crime when the doctor went to the seminar room to rest, several reports quoted CBI officials.

Though Sanjoy was arrested, West Bengal junior doctors suspect there are more than one behind the incident.

The case, which caused a massive uproar across the country, is currently being probed by the CBI under the monitoring of the Supreme Court.

The CBI has arrested ex-RG Kar principal Sandip Ghosh, who was already in custody for alleged financial irregularities in the hospital, and a cop in connection with the case.

Prior to CBI's investigation, the state administration came under the scanner over its alleged cover-up, delay in filing FIRs, demolition work near the crime scene, posting of Ghosh to the same post at another college after his resignation from RG Kar.