The most senior policeman in Britain when Princess Diana died has been accused of being part of a conspiracy to murder her.
Police had several meetings with Diana about reinstating protection
Lord Condon, the former Metropolitan Police chief, said the allegation was "abhorrent" and "disgusting".
Earlier he told her inquest he thought the princess would still be alive if she had retained her police protection.
He had begged her to reinstate her protection but she refused to change her mind as she did not trust police.
He said: "If, as my wish, she would've had police protection in Paris, I'm absolutely convinced those three lives would not have been tragically lost."
Princess Diana and her companion Dodi Al Fayed died with their driver Henri Paul in a car crash in Paris in 1997.
Lord Condon emphatically denied suggestions from Michael Mansfield, QC counsel for Dodi's father Mohamed Al Fayed, that he had been involved in a conspiracy to murder her.
At the High Court on Wednesday, Mr Mansfield questioned Lord Condon about a note he had seen from Diana to her lawyer Lord Mishcon, in which she revealed fears she would be killed in a car crash.
The lawyer had handed it to Lord Condon 18 days after the fatal crash, but it was not passed to the Royal coroner until 2003.
The princess decided she wanted protection to stop in 1993
Mr Mansfield asked why Lord Condon had not disclosed the note earlier.
Coroner Lord Justice Scott Baker intervened and twice asked Mr Mansfield if he was suggesting Lord Condon was part of a criminal conspiracy.
To this Mr Mansfield replied: "Yes I am."
Lord Condon said: "That is the most serious allegation that has been put to me. I unequivocally, totally refute that. You are in effect, accusing me of being a murderer.
"It is a disgusting suggestion, that is a blatant lie."
The princess had first indicated she wanted to have her protection removed in December 1993, the former Metropolitan Police commissioner said.
A series of meetings had then taken place, up to January 1994, to try to get her to reconsider, the court heard.
Lord Condon said he had attended a "critical" meeting on 14 December 1993, in which he had said he was "really concerned" the security was going to be removed.
The peer was himself involved in a serious accident the following day, and then remained unavailable for about three-and-a-half to four weeks.
He said: "I have often thought back, if that had not been the sequence of events I might have demanded face-to-face meetings with her. But I honestly don't think it would have changed her mind."
The court also heard claims from a former employee of the Al Fayed family that he had been asked to falsify elements of Diana's relationship with Dodi Al Fayed.
Reuben Murrell was head of security at Villa Windsor, Mr Al Fayed's Paris home.
Mr Murrell told the inquest he came under pressure from his employer to exaggerate the nature of the couple's relationship in order to support the theory that they had serious plans to marry.
On the day of the crash, Mr Murrell said the couple called into the villa for 28 minutes, apparently in an attempt to lose the paparazzi who had been following them.
He said he was later told to falsify two elements of the visit at the specific request of "the boss".
Mr Murrell said: "I was told to mention the presence of an interior designer, and to indicate that he was part of the visit to Villa Windsor, and to indicate that they were there for a considerable period of time, possibly all afternoon."
In the months following the crash, Mr Murrell left his job and sold his story and some CCTV pictures of the visit to a newspaper.
Asked why he quit, Mr Murrell said: "I could see how the story - the part I knew of, surrounding the Villa Windsor visit - was being elaborated.
"I considered my own integrity at that stage to be in question."
The inquest also heard the princess told Barbra Streisand that her royal in-laws thought she was "mad".
The Hollywood star had asked her if she was happy during the film premiere for The Prince Of Tides in February 1992.
Her friend and interior designer Roberto Devorik, who was also at the event said it was then that Diana spoke of her fears,
Mr Devorik told the inquest: "During the conversation with Miss Streisand the princess indicated that her in-laws 'think I'm mad and my husband agrees with them' and he wanted her to be treated in a home."