Central Forensic Science Laboratory (CFSL, Chandigarh has, in an RTI reply, said that the recording in CD is "not original" and "post production edited version". The CD was received by a leading daily at its office on April 13 by some unknown sender.
After the CD came into circulation, Shanti Bhushan had filed a complaint with Delhi Police on April 14, alleging that it was fabricated and denied having any conversation with Mulayam and Singh.
Delhi Police got the CD examined at CFSL, Delhi and CFSL,
Chandigarh besides CERT-In, a department under the ministry of
communications and information technology which gave divergent
opinions after analyzing the CD.
The CFSL, Delhi report was received by Delhi Police on April 20 in which it said "the recorded conversation in the CD could not have been tampered with".
On April 21, the case was transferred to the special cell and
the CD, received in a sealed cover from CFSL, New Delhi, was sent
to CFSL, Chandigarh for second opinion.
With two different versions on the analysis of the CD, the matter was sent to CERT-In, which in its report on May 28, said the "audio file containing the conversation was continuous with no sign of abrupt changes or editing marks."
After getting these reports and questioning of people involved the case, Delhi Police sought permission of the court to close the case filed on the complaint by Bhushan saying there was no substantive evidence to prove the offence of forgery as alleged by him.
The CFSL, Chandigarh report now made public under the RTI Act shows that the CD sent to the Laboratory by the Delhi Police carried only one audio file of one minute and 55 seconds which was created on April 15, 2011 while the CD was created on April 17.