This is the email that proves Sinn Fein knew about a progressing deal to sell Nama's assets in Northern Ireland.
The £1.2bn sale - Northern Ireland's largest ever property deal - was of property loans to US investment firm Cerberus by Nama, the Republic's "bad bank".
Deputy First Minister Martin McGuinness told Stormont's finance committee on Wednesday that he was "not aware" of discussions between then Finance Minister Simon Hamilton and First Minister Peter Robinson with Irish Finance Minister Michael Noonan about the NI portfolio back in 2013.
Mr Robinson had contended that Mr McGuinness was aware, and said that there was a paper trail to prove it.
Mr McGuinness told the committee on Wednesday that he asked his officials to do a "very thorough check", and said it was concluded that "no such paper trail exists".
However, pictures have emerged of an email sent by David McCreedie from the First Minister's Office in Stormont Castle to Mr McGuinness' then special adviser Dara O'Hagan, including a memorandum of understanding about the acquisition of the Nama assets.
The email is dated December 2013, when Pimco was then in negotiations to buy the portfolio, and opens with the words "as discussed".
During Wednesday's finance committee meeting, DUP MLA Jim Wells told Mr McGuinness about the existence of the email.
He asked the Deputy First Minister: "Are you telling me that Dara O'Hagan did not make you aware of the existence of that memorandum of understanding?"
Mr McGuinness indicated that he was not aware of the email.
"I do not know the veracity of what you are saying, but, working on the basis of what you are saying, if Dara O'Hagan judged, as a senior adviser in the Office of the First Minister and Deputy First Minister, that I should not be involved in that, it would not have come to me," he said.
Mr Wells further pressed: "We are talking about a £1.25bn transaction here; £5bn-worth of assets. It is the largest property holder in Europe... a company that holds a high percentage of all the property in Northern Ireland. Are you saying that Dara O'Hagan, a former MLA and a senior adviser, decided that it was not for your attention?"
Mr McGuinness responded: "If she thought that she was sufficiently concerned that this was something that I, as Deputy First Minister, should not be associated with, it was perfectly legitimate for her to do that. I would advise her to do that all the time, which you, as a former Health Minister, would know."
Mr Wells said if a special adviser in the Department of Health "had failed to provide me with details of a document involving £5bn, heads would have rolled".
He added: "We are talking about £5bn of assets in Northern Ireland, and you say that that was never passed to you, and you have no knowledge of it."
It is understood that Ms O'Hagan has moved from her role as special adviser in OFMDFM to advise Culture Minister Caral Ni Chuilin.
The Belfast Telegraph approached Sinn Fein yesterday to ask about this email.
A spokesman did not respond formally, but pointed out Mr McGuinness' evidence to the committee on Wednesday when he said for a memo to be valid coming from the Office of the First Minister and Deputy First Minister, it would required both the Deputy First Minister and the First Minister's consent or, absent that, the consent of the principal private secretaries on our behalf.
"That did not happen," Mr McGuinness told the committee.
Mr McGuinness said there were "very serious questions" about what capacity Mr Robinson was acting in with regard to the Nama loan sale.
The finance committee's probe was set up after Mick Wallace TD claimed impropriety in the sale of Nama's northern assets.