The then chief medical superintendent of the hospital, S C Singhal, reported the matter to the Noida Police immediately. He even informed probing agency — the Central Bureau of Investigation — that a register detailing the pathology findings of Arushi Talwar had disappeared from the department’s cabinets. In fact, the hospital discovered the files were missing after the CBI had asked for the original medical reports.

The CBI has made several trips to the hospital since but has been unable to trace the register. Officers are checking, sources said, if it has been carelessly misplaced.

The new chief medical superintendent, Renu Srivastava, said: “The register went missing when S C Singhal was in charge. He is retired now and I am new to the post. We have not found the register in the hospital nor on any staff. We fully cooperate with the CBI and the police teams whenever they want to go through the files.”

It is learnt the CBI is now going through the inventory of all case documents to check if any other has gone missing when investigations were still fresh. The CBI is also trying to sniff out any possible liasion between the Noida Police and hospital staff.

Suspect Rajkumar’s lawyer Naresh Yadav said: “Rajkumar, Krishna and Mandal were all in the CBI’s or the police’s custody after the murders. Out on bail, Rajkumar and Krishna immediately left for Nepal. The reports went missing much later, in October. Only an insider, or someone of influence, can have access to these documents.”

Not much has progressed on the case so far. The murder weapon has not been found, nor the mobile phones of Aarushi and Hemraj. A senior CBI officer clammed up when asked if the agency has any evidence to pin on the suspects. He would not say either if the CBI has set any deadline to file the chargesheet. It has already missed the initial date of September 10.

Sources also said no CBI team has visited Nepal so far. Naresh Yadav said: “Rajkumar keeps calling me from Nepal. No CBI officer has contacted him yet. Rajkumar is ready to come to India whenever called.”

Arushi Talwar, the 14-year-old daughter of doctor couple Rajesh and Nupur Talwar, was found dead in their Jalvayu Vihar apartment in Noida on the morning of May 16. The initial suspect was the family help but that theory fell flat when Hemraj’s body was discovered on the apartment’s terrace the next day. Rajesh Talwar was earlier the prime suspect but the CBI let him go on July 11 — unable to find any evidence that would have linked him to the murders.

The CBI then arrested the three helps Rajkumar, Krishna and Vijay Mandal. Krishna worked as a compounder in the Talwar clinic, Rajkumar was employed by their family friends doctors Praful and Anita Durrani, and Mandal worked in the locality.