A leading insolvency expert has raised concerns about a conflict of interest on the part of Rangers administrators Duff & Phelps.
David Grier, a senior Duff & Phelps partner, had said he was unaware of the Ticketus deal until August 2011.
But the BBC has seen evidence that he knew a deal was under way in April, before Craig Whyte's takeover. Insolvency expert Roger Isaacs said it was the starkest conflict of interest.
Duff & Phelps denied the claims.
Former Rangers director, Paul Murray, has called for regulators to investigate the role of the administrators.
Mr Whyte completed the takeover of Rangers on 6 May 2011, but came under serious criticism after it was revealed he had used the London finance firm Ticketus to fund the purchase of the club by selling off most of the next three years' worth of season tickets.
Emails revealed in a BBC Scotland documentary - Rangers: The Men Who Sold the Jerseys - show that Mr Grier ordered an invoice to be raised to Ticketus in June.
The Ticketus deal, if it stood, would make Rangers a much less attractive proposition to any potential buyer, since more than half of the club's income stream for the next three years had gone.
Mr Whyte called in administrators on 14 February, after running up debts to HMRC of up to £15m. His choice of administrators, Duff & Phelps, were appointed with court approval.
The administrators, Paul Clark and David Whitehouse, initially told the media that their partner, Mr Grier, had some prior involvement with Mr Whyte's takeover bid.
But when asked by the BBC whether the firm had been involved in or was aware of the Ticketus transaction, Mr Grier said: "It was September, when - I think it was probably August time actually - when there was a payment that was due back to Ticketus that was not planned into the cash flow that we were working to and which we were presenting to HMRC, so that set a series of hares running."
Mr Grier added: "And we said - 'well we don't understand anything about any commitments to Ticketus or involvement with them'."
He was then asked: "They were never involved in the financing of this purchase, as far as you were concerned, that is?"
Mr Grier replied: "Not at all. That wasn't in our terms of engagement."
However, Wednesday's documentary - Rangers: The Men Who Sold The Jerseys - casts serious doubt on this claim.
An email from Mr Whyte's lawyer, Gary Withey, to Mr Whyte and Mr Grier was sent on 19 April 2011, two weeks before the deal was completed.
The message is entitled 'Ticketus draft' and concerns the completion of the takeover.
The email states that when Mr Whyte's company takes "board control the assignation documents will be released by the bank and the Ticketus agreements will become unconditional".
'Conflict of interest'
The BBC showed this to forensic accountant and licensed insolvency practitioner Roger Isaacs, from the Institute of Chartered Accountants for England and Wales.
Mr Isaacs said: "Well, on the face of it this email seems to suggest that David Grier knew about the Ticketus arrangement.
"And therefore, in those circumstances, given that he was a partner of Duff & Phelps, I'm surprised that that involvement wasn't firstly disclosed, and secondly doesn't give rise to the sort of conflict of interest that I would have expected to have precluded Duff & Phelps from accepting the appointment as administrators."
Duff & Phelps have launched a legal action claiming Mr Whyte and his lawyers, Collyer Bristow, engaged in a conspiracy to defraud the club of £25m.
Its case is based on the claim that at a crucial meeting just days before the deal was signed on 24 April, it failed to declare that the money being used to complete the purchase of Rangers was coming from Ticketus, not Mr Whyte.
But the BBC has obtained the minutes from that meeting which clearly show that Duff & Phelps partner, Mr Grier, was present at that meeting.
Mr Isaacs added: "So this suggests that David Grier was in attendance at the very meeting in relation to which his partners are now taking legal action.
"Which if true, is one of the starkest conflicts of interest I've ever seen."
In a statement, Paul Clark, joint administrator with Duff & Phelps, said the allegations were untrue and a "distortion of the facts".
He said discussions were under way with their solicitors with a view to bringing legal proceedings against the BBC.
Mr Grier has also been involved in the club's administration process, although has played a background role.
In response to the allegations, Mr Grier also issued a statement.
In it he said: "I categorically deny that at the time of the Craig Whyte takeover of Rangers, I had any knowledge that funds from Ticketus were being used to acquire the club.
"However we were party to discussions regarding Ticketus as a recognised source of short-term working capital. Material information was withheld to us."
Mr Grier and the Rangers administrators David Whitehouse and Paul Clark were part of a company called MCR which was bought over by Duff & Phelps.
In a separate statement Mr Clark said: "I thought that MCR became aware of the full scale of Ticketus funding in July or August. I gave an honest answer to the best of my recollection as I had not been closely involved in the Rangers takeover work at the time.
"There is a world of difference between knowing that Ticketus was a potential source of working capital funding for the club … and knowing that funding from ticket sales had been effectively used to purchase the club."
'Matter of urgency'
Speaking on Newsnight Scotland, Paul Murray, whose Blue Knights Consortium recently failed in its attempts to buy Rangers, said: "Whoever regulates insolvency practitioners, I think, has to look at this as a matter of urgency.
"I think the problem from the club's point of view is that we don't have a lot of time to do that."
He added: "I think for the Rangers fans to have confidence in the process over the last three months, that has to be looked at immediately."
Rangers: The Men Who Sold the Jerseys was broadcast on BBC One Scotland on Wednesday 23 May, and will be available afterwards for one week on the iPlayer.