Shortly after the family members of late Bollywood actor Sushant Singh Rajput wrote to the Central Bureau of Investigation (CBI) demanding the reconstitution of a medical team, the federal agency sleuths were once again in Mumbai.

A CBI source said that the investigation into Sushant's death is still continuing and all the aspects are being looked into "meticulously".

"As per the demand of the investigation, either a team or a set of officers visit Mumbai at regular intervals, besides the agency officers from the Mumbai branch present there," the source added.

The source, however, refused to share the name of the officials of the agency who arrived in Mumbai from Delhi.

The source said that the CBI sleuths reached Mumbai to collect more details in the case.

The remarks came after Varun Singh, son of Sushant's lawyer Vikas Singh, wrote to CBI chief R.K. Shukla after the Bombay High Court granted bail to Sushant's girlfriend Rhea Chakraborty, late actor's house manager Samuel Miranda and personal staff Dipesh Sawant in a narcotics related case.

Rhea was arrested on September 8 after three days of questioning. However, the high court denied bail to her brother Showik.

Varun Singh, in his letter to the CBI chief, referred to the report of the All India Institute of Medical Sciences (AIIMS) rejecting the possibility of murder and claimed that the forensic examination conducted by the forensic board is faulty.

"I have been reading in the media about the report submitted by AIIMS to CBI with regard to the opinion expressed by CBI in the matter of the death of Sushant Singh Rajput on June 14, 2020. I have also seen some doctors who were part of the AIIMS team come on TV and make statements with regard to the forensic examination done by the team," he said.

The letter said that in spite of several efforts to get a copy of the report, there has been no response by AIIMS forensic board head Dr Sudhir Gupta and "I am accordingly writing this letter on the premise that the news report regarding the AIIMS opinion is correct".

The leaked forensic report, if correct, amounts to drawing a biased and boastful conclusion from insufficient evidence, Varun Singh said.

The CBI registered a case on August 6 on the recommendations of the Centre. Sushant was found dead on June 14 in his Bandra flat.

The CBI team had reached Mumbai on August 20, a day after the Supreme Court gave its nod for the federal agency probe.

The AIIMS forensic team also visited Mumbai and recreated the crime scene at Sushant's apartment and recorded the statement of several people.

The Narcotics Control Bureau, however, registered a case after the Enforcement Directorate (ED) probing the money laundering angle into Sushant's case found alleged drug chats.

Jaikush Hoon, a criminal lawyer commenting on the bail to Rhea, Miranda and Sawant by the High Court, said that the NCB has failed to build its case against the three under sections 27(a), 22(c), 22(b), 20 (b)(c) of the NDPS Act,1985.

"In my opinion, the mastermind is out on bail now. It is a big setback to NCB and Sushant case as well. The agency was after a drug syndicate of 1.35 lakh crore in the country and this order would come as a relief to lot of people who are active or facilitating member of the crime syndicate," he said.

He said tampering with evidence and influencing of witnesses could be on the cards.