Mumbai: In a surprise development in the 'letter bomb' dropped by former Mumbai Commissioner of Police Param Bir Singh, the Chief Ministers Office on Saturday said that the letter was not received from the IPS officers known official email id.

In view of the discrepancies in the known email id of Singh, the home department is making efforts to contact him (Singh) to verify the antecedents of the unsigned letter, said a CMO spokesperson.

On the other side, Home Minister Anil Deshmukh charged Singh with conspiracy and threatened to file a defamation case.

Deshmukh, in a detailed rejoinder, accused Singh of "lying", making the false accusations as part of a "conspiracy" hatched to discredit him (Deshmukh) and the Maha Vikas Aghadi government to save himself from any action in the SUV case and the case related to the death of Mansukh Hiran.

The SUV case refers to the explosives-laden Scorpio that was found near industrialist Mukesh Ambani's residence in Mumbai last month. Thane-based businessman Mansukh Hiran, who was in possession of the Scorpio, was found dead under mysterious circumstances on March 5.

"Why was Singh quiet for so many days after (API) Sachin Vaze's arrest? After realising that he would be removed as the CoP on March 17, a day earlier (March 16) Singh called ACP Sanjay Patil, asked him some questions and got the answers he wanted," Deshmukh pointed out.

Dismissing the contents of the letter as part of a larger conspiracy by the IPS officer, Deshmukh said that Singh wanted to collect evidence systematically through WhatsApp chat, which showed that he was impatient as he repeatedly asked questions to ACP Patil.

Deshmukh also called upon Chief Minister Uddhav Thackeray to order an impartial probe into the allegations made in Singh's letter.

In a sensational twist to the SUV case, Singh on Saturday hit out at Deshmukh by virtually alleging that the minister wanted his team member, arrested cop Sachin Vaze, to 'collect' Rs 100 crore per month from bars and hookah parlours.