Thirty days have passed after the body of a woman medic, raped and murdered, was recovered from state-run RG Kar Medical College and Hospital here, but investigators are still clueless about what led to the crime that has opened a can of worms.

CBI detectives, who took up the probe into the case after the Calcutta High Court transferred the investigation from the Kolkata Police on August 13, said that they were unable to join several dots due to lack of evidence from the crime scene, a senior official said.

This, he said, has affected the investigation of the crime which came to light after the body of the trainee doctor was found in the seminar room of the hospital on August 9.

The police arrested Sanjoy Roy, a Kolkata Police civic volunteer, the next day in this connection.

It was found during the investigation that former principal of the hospital Dr Sandip Ghosh ordered the demolition of a restroom and a toilet close to that seminar room on August 10. As a portion of the two areas were demolished by the PWD, it is suspected that key pieces of evidence were lost.

Besides, a video surfaced on social media showed the seminar room was crowded with people soon after the body was found. The police, however, claimed that the spot inside the room was cordoned off.

The CBI has grilled witnesses including Ghosh, other doctors, officials, security guards and the arrested prime accused, Sanjay Roy.

"There is a lack of evidence in this case. That is the reason why our detectives are unable to come to a conclusion. From circumstantial evidence, questioning of people and the DNA evidence do not show involvement of multiple persons in the sexual assault on the woman," the officer told PTI.

He said that the forensic tests conducted at the Central Forensic Science Laboratory (CFSL) confirmed a match between the DNA of the victim and the arrested civic volunteer.

"Separate DNA profiling on samples gathered from the victim and Roy and the DNA comparing with other seized evidence from the crime scene also corroborated the CFSL report," he stated.

Echoing the claims of the CBI about tampering with evidence, the parents of the deceased also alleged the same.

"When we reached there (after her death), we found several people inside the seminar hall, one policeman guarding the entrance of it and many more standing outside. It can be assumed that the entire scene was very carefully arranged. Going by the brutality of the crime, the scene could not be so," the mother of the victim said.

The counsel of the accused claimed that her client had been framed to shield the actual criminals.

In the case of financial irregularities in the hospital for which the ex-principal Ghosh was arrested along with three others, the CBI officer said they found more names who were involved.

"More people were involved in the irregularities which were carried out in a well-planned manner," he said, adding that at times there were no footprints of the financial misconduct.

The central probe agency has submitted before a court that Ghosh had played a vital role in siphoning off funds and orchestrated 84 illegal appointments during his tenure at the hospital as the principal from 2022 to 2023.

The Enforcement Directorate (ED) is also conducting a simultaneous investigation of the financial irregularities case revealing that the former principal and his wife own a luxurious bungalow in the South 24 Parganas district of West Bengal.

They also discovered more property owned by Ghosh and confiscated several "important" documents during search operations at his residence, as well as those of his relatives and accomplices.

The ED has filed an ECIR against Ghosh and started their probe. An ECIR is generally filed by the ED as the case information report. It is similar to a first information report (FIR) in criminal cases.

Media reports also claimed that a racket was functioning in the health department, which controls various aspects of the administration including transfers. The racket also allegedly indulges in unfair means during examinations of students.

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