Kolkata: Mystery over the burgled Nobel medallion of Rabindranath Tagore, missing since March, has deepened with a letter reaching the Visva-Bharati Vice-Chancellor's office at Santiniketan recently from a person who sought to return it.

The letter written by one Jasimuddin from Kolkata informed Vice-Chancellor Sujit Basu that the Nobel medallion was in his custody and that he would like to return it.

''Nobel medal is with me. This I would like to return. Suggest how to return it,'' the letter bearing a Kolkata PIN code but no address said, University sources said today (June 30, 2004).

The mystery letter, however, bore no address of the sender and came barely days after marks-sheet scam accused former V-C Dilip Sinha's disclosure to the CID that the stolen Nobel medallion was still at Santiniketan and had not been taken out of the area, the sources said.

CBI sources in Santiniketan said Basu had handed over the letter to the investigating agency, now camping there in connection with the Nobel heist, for inquiry.

However, a CBI team visited some areas in Kolkata following the PIN code of the letter ''but none in the name of the sender could be found'', the sources said.

Investigators, alerted by Sinha's startling disclosure, would further interrogate Sinha immediately on his release from state-run S S K M hospital where he was admitted with chest pain complaints soon after his arrest on June 24 in connection with his involvement in the marks-sheet scam.