An inquiry into how the BBC secured a 1995 interview with Britain's Princess Diana, in which she disclosed details of her failed marriage, is expected to release its report on Thursday into accusations she had been tricked into taking part.
The BBC set up the investigation, headed by former senior Court judge John Dyson, in November following allegations from Diana's brother Charles Spencer that forged documents and "other deceit" were used to persuade him to introduce Diana to journalist Martin Bashir.
The Daily Telegraph newspaper reported that the inquiry would conclude that Bashir deployed deceitful methods and criticise BBC bosses at the time.
During the interview, watched by more than 20 million viewers in Britain, Diana shocked the nation by admitting to an affair and sharing intimate details of her marriage to the heir to the throne, Prince Charles.
Last week, the BBC announced that Bashir was leaving his current job as the publicly-funded broadcaster's religious affairs editor because of ill health. He has made no comment on the matter.
The interview with Diana, who died in a Paris car crash in 1997, came at a nadir for the royal family and was the first time she had made public comments about her doomed marriage.
Her remark that "there were three of us in this marriage, so it was a bit crowded" - a reference to Charles rekindling his relationship with his Camilla Parker Bowles, now his second wife - was particularly damaging to the Windsors.
Spencer says Bashir made had told him his sister to get her to agree to the interview that Diana was being bugged by the security services and that two senior aides were being paid to provide information about her.
He says Bashir provided fake bank statements to back up the claim.
Both Diana's sons, Prince William and Prince Harry, have welcomed the investigation as a chance to find out the truth of what had happened.