The investigating agency, which was directed by the Calcutta High Court to probe the death, is expected to apprise the court next week of its findings and file a report in this regard, sources said.

In the wake of a raging controversy over the alleged role of policemen in collusion with the businessman' family, the issue was taken up in the Calcutta High Court, which had directed the CBI to go into the circumstances of the unnatural death of the young man, whose body was found on the rail tracks near Dum Dum on September 21 in 2007.

CBI sources said the agency had retrieved the last suicide note from the computer recovered from the kin of Rehman who died under mysterious circumstances after his wife was taken back to her maternal home.

CBI gathered this data from the computer which was recovered from the house of Rehman's maternal aunt, who after his death on September 21 had deleted the letter, the CBI sources said.

They said the letter was retrieved at the forensic laboratory in which Rehman had stated the condition of his mind and non cooperation from the Todi family in allowing him to meet his wife, Priyanka.

According to the CBI probe, a ‘close’ relative of Priyanka, whom the victim had married, had allegedly used pressure tactics to drive Rehman to such a stage where he took the extreme step of committing suicide.

In October, the CBI had registered a case against Todi, and others under Section 302 of the Indian Penal Code (murder).

The agency checked the call records and examined all the family members of the victim as well as Priyanka, including Todi, during its three month-long investigations.

Besides the friends of Rizwanur, the police officials who allegedly had ‘pressurised’ Rehman and Priyanka to separate were also examined. Sources said CBI might also book two police officials for alleged abetment to suicide.

The CBI has subjected Priyanka's uncle Pradeep Todi, an activist of an NGO, Papu and a relative of Rehman under the lie detector test to ascertain whether the allegation that Todi's family paid Rs 11 lakh as separation fee was correct.

The CBI said while there was no direct evidence but circumstantial evidences pointed out that the money had been paid at a hotel in Kolkata -- which was also shared by a kin of the deceased computer graphics teacher. The sources said that the kin might also be booked for conspiring to abetment of suicide.

The Calcutta High Court had directed the CBI to go into the circumstances of the unnatural death of the youth whose body was found on the rail tracks near Dum Dum on September 21.