Fraser, 48, from Elgin in Moray, is challenging his conviction for murdering his wife Arlene in 1998.
He was found guilty in 2003 of murdering the 33-year-old, whose body has never been found.
Alan Turnbull QC, who prosecuted the case, was unaware of a police statement until late in 2005, the court was told.
Peter Gray QC, for Fraser, said Mr Turnbull's statements on the issue to a subsequent high level inquiry demonstrated the potential of a police officer's information to undermine the case.
Fraser's trial heard that Arlene's engagement, wedding and eternity rings went missing on the day she disappeared but then turned up in the bathroom of her home several days later.
It was claimed her husband had placed them there.
Mr Gray said that, in a statement, Constable Neil Lynch had reported seeing the rings on the night she disappeared or the day afterwards.
Mr Gray told the court: "In so far as the trial depute (Mr Turnbull) is concerned, it is quite clear that he was not aware of the content of the draft precognition until October 2005."
Referring to statements said to have been made by Mr Turnbull to a Crown Office inquiry, Mr Gray said: "The significance which he then attached to the discovery from Police Constable Lynch speaks volumes."
Arlene Fraser's body has never been found
Mr Gray said the prosecutor's comments were "perhaps the clearest demonstration" of the extent to which officer's information "had the potential to fundamentally undermine the Crown case".
Earlier, the appeal court heard how Mr Turnbull told the inquiry: "If, in the course of the trial, I had been shown Lynch's precognition, I honestly would have fainted, so inconsistent would it have been with my thinking and my view of the evidence."
The court later heard that a policewoman broke down in tears during a conversation last year with the current procurator fiscal of Elgin, Sharon Ralph, over the case.
A "fragile" Pc Julie Clark was said to have potentially crucial information about the rings.
Mr Gray said if the evidence about that conversation was correct, PC Clark was "clearly" under pressure to say nothing about what she apparently knew.
The court heard Mrs Ralph said in a statement that Ms Clark claimed to have seen recent press coverage of the case and suddenly broke down.
Mr Gray read from the statement, which said: "She started saying things like 'It's been really terrible, I'm going to be branded a grass'."
She was also alleged to have said: "My career is over, it's awful."
The court heard Mrs Ralph said Pc Clark nodded when asked if she had seen the rings.
The statement also read: "I then asked, 'Were you told not to say anything?' and she then nodded affirmatively."
The hearing, which began before the Lord Justice Clerk Lord Gill and lords Osborne and Johnston on Tuesday, continues and is set to last about three weeks.
The judges will deliver their written judgement some time later.
Fraser, who was ordered to serve at least 25 years of a life sentence, was released on bail in May last year.