Rahul Mukerjea was also allegedly facing threat from his step mother Indrani which he had conveyed to his father Peter Mukerjea through an email sent about a year before the murder of his girlfriend Sheena Bora.
CBI which is probing the murder of Bora has attached this conversation in the supplementary charge sheet which mentions that Peter knew that his wife Indrani has allegedly issued threats to his son Rahul and her daughter from her first marriage Sheena, sources said.
Fearing threats, Sheena and Rahul had taken a backup of all the mails, messages, documents for safekeeping, they said.
In the mail dated April 13, 2011, Rahul told Peter, "On several occasions, we have received threats from Indrani...I have protected myself and Sheena by documenting mails, history, conversations and messages included."
He wrote that he had put these for safekeeping and threatened to make them public "should anything happen to either Sheena or me", the mail alleged.
CBI has alleged that Peter was actively involved in the conspiracy to murder Sheena which was hatched by Indrani, her second husband Sanjiv Khanna and driver Shyamvar Rai who all have been arrested by the agency.
Peter was also told by Rahul that he was not sure if messages coming from his father's phone were actually sent by him or not.
Rahul had accused his father of allegedly using the email accounts of Indrani and Khanna's daughter Vidhie to send mails to Sheena, it alleged.
"Please also remember that you yourselves involved young Vidhie in all of this by using her email account to send emails in the first place and by giving her the phone when Sheena wanted an explanation from Indrani," he said in the mail.
Rahul had told Peter that Indrani was "bad-mouthing" him and also pressuring a media company where he was trying.
"After all the things your wife has said about me, and all the threats she has made, and after all the attempts she has made to disrupt my progress, telling a load of lies about me and trying to have me thrown out from my flat. Then also pressuring the (media company) people," he had told Peter in his mail which has been attached by CBI in the charge sheet.
CBI had mentioned in the supplementary charge sheet that both Peter and Indrani wanted separation of Rahul and Sheena who were in a relationship.
The agency has submitted the charge sheet, running into 500 pages and listing 52 witnesses.
"We have mentioned in the charge sheet that the process of separating Sheena and Rahul had started since 2009 and as they did not budge, the duo (Indrani and Peter) planned to kill her," a CBI official said.
Peter was arrested on November 19 for his alleged role in the murder conspiracy. He was in CBI custody for two weeks. Indrani is the prime accused in the case.
On November 19, CBI had filed a charge sheet against Indrani, Khanna and Rai for murdering Sheena and disposing of her body.
As per the charge sheet, Indrani and Peter were unhappy with Sheena and Rahul's relationship, and they had told their friend Pritul Sanghvi that 'this relationship was not correct'.
Sheena (24), Indrani's daughter from an earlier relationship, was allegedly strangled in a car by Indrani on April 24, 2012 and her body was burnt before it was dumped in a forest in adjoining Raigad district.