Papua New Guinea's former attorney-general says Peter O'Neill's attempt to explain a crucial letter in a corruption case undermines the prime minister's later claim that the letter was forged.
Mr O'Neill has confirmed to the ABC that he signed a letter in 2013 that clarified the intent of an earlier directive to process legal bills, but insists he misunderstood what he was signing.
Mr O'Neill says his chief of staff, Isaac Lupari, drafted the letter for him to sign but Mr Lupari has refused to confirm that he was the author.
"If [Mr O'Neill] says that he didn't sign the first letter, then how is it that in the second letter he refers to the first letter by date?" former attorney-general Kerenga Kua said.
Mr Kua was dismissed for questioning Mr O'Neill's leadership but remains an MP for Sinasina-Yonggamugl.
A legal and political scandal has raged in PNG since police served Mr O'Neill with an arrest warrant for official corruption on June 16.
One of the key pieces of evidence is a letter dated January 24, 2012 directing the Ministry of Finance to process $28 million to Paraka Lawyers for legal work investigators say is mostly fabricated.
Mr O'Neill has consistently said the letter is a forgery and did not come from his office.
PNG's anti-corruption agency, Investigation Task Force Sweep, has challenged that claim, saying a Sydney-based forensic lab has confirmed the signature is that of Mr O'Neill.
However, a second letter dated May 15, 2013 and signed by Mr O'Neill makes reference to the earlier letter.
"It has been brought to my attention that your [Finance] Department is being instructed to settle outstanding legal fees for the above legal Firm on a basis of my letter dated 24th January, 2012 (copy attached) to the Minister for Treasury," wrote Mr O'Neill.
"I am very concerned that the intent of my letter has been taken out of context. In this case, I simply referred the matter to the Ministry for Treasury."
The letter dated May 15, 2013 makes no reference to a forgery.
The ABC asked Mr O'Neill how he explained the official acknowledgment of a document he later claimed was a fake.
Mr O'Neill, through one of his political advisors, said the second letter was drafted by Mr Lupari and given to him to sign.
Mr O'Neill confirmed he did sign the May 15, 2013 letter.
However, Mr O'Neill says neither he nor Mr Lupari was aware the first letter was a forgery and had not come from the PM's office.
When contacted by phone, Mr Lupari refused to confirm or deny that he personally drafted the second letter.
"This office drafts a lot of letters," Mr Lupari said, after repeated attempts to clarify the authorship of the second letter.
While this paper trail and its authenticity has been a key part of the corruption allegations, the chairman of Investigation Task Force Sweep says he has more evidence against Mr O'Neill that just the two letters.
"We cannot run a case entirely on that, we have other material to support the case," Sam Koim said this week.
"That is the reason some people really want to see what we have, so that they can run to court as well."
There are several court cases currently being heard in relation to the disputed Paraka legal bills and the arrest warrant for Mr O'Neill.
PNG's National Court will this week hear a challenge to the Cabinet decision to disband Task Force Sweep.
Mr O'Neill created Task Force Sweep in 2011 to investigate the Paraka affair and often praised the group's work, but dismantled it last month after being served with an arrest warrant for official corruption.
Mr Koim said his investigation had found 97 per cent of the 2,716 bills paid by the government to Paraka Lawyers were "inflated, falsified, bogus".
The arrest warrant for Mr O'Neill has been deemed valid by the National Court, but the police commissioner appointed by Mr O’Neill in the wake of this scandal says he will not be arresting the prime minister