Indrani Mukerjea allegedly killed her daughter Sheena Bora in April 2012.
The CBI, probing the Sheena Bora murder case, is likely to a file charge sheet against Indrani Mukerjea and two other accused by end of this month.
"As per the provisions of Code of Criminal Procedure (CrPC), we have to file the charge sheet in the case within 90 days of the arrest of the accused, otherwise the accused are eligible for a default bail," said a CBI official.
Apart from 43-year-old Indrani Mukerjea, the accused include her former husband Sanjeev Khanna and her former driver Shyamvar Rai.
Indrani Mukerjea and Shyamvar Rai were arrested on August 25 and Sanjeev Khanna the next day. The charge sheet will be filed in a court of metropolitan magistrate in South Mumbai.
"We have prepared a watertight case and the charge sheet will include the statements of witnesses, statements of certain witnesses recorded before the magistrate (which they cannot retract), call data records, DNA samples, besides other documents," the agency official said.
The case is being investigated by the Special Crime Branch of the CBI.
A local court had on November 7 extended the judicial custody of the trio till November 20 and also allowed the agency to interrogate the accused in jail till November 17.
Indrani Mukerjea, along with Sanjeev Khanna and Shyamvar Rai, has been accused of murdering Sheena Bora (24), her daughter from her previous marriage, and disposing off her body at a Raigad forest in April 2012, about 84 kilometres from Mumbai.
According to the police, Sheena Bora was allegedly strangled in a car, then her body was burnt before being dumped in the forest in neighbouring Raigad district.
The Maharashtra government had transferred the case to CBI in September, saying it as an attempt to clear all doubts over the probe and the officers involved as the then Mumbai police commissioner Rakesh Maria had personally led the probe.
During their investigation, police suspected that Indrani Mukerjea had been upset with Sheena Bora's relationship with Rahul, son of her husband and former media tycoon Peter Mukerjea, who was also quizzed.
Indrani Mukerjea, lodged in Byculla jail for women, was recently hospitalised after her platelet count dipped drastically, giving speculation that she was suffering from dengue. However, doctors at JJ hospital later made it clear that she had not contracted dengue.
Earlier, on October 2, she was rushed to JJ Hospital from the prison in an unconscious state, fuelling speculation that she had overdosed on anti-depressant drugs. But, the probe by Inspector General (prisons) ruled out the possibility of drug overdose, poisoning or suicide bid.
On October 6, Indrani Mukerjea was discharged and sent back to jail.