One of the last photos of Diana, Princess of Wales, shows only a blur of her famous blonde hair in the back seat of a Mercedes as it leaves the Ritz Hotel in Paris on August 30, 1997.
In the driver's seats is Henri Paul, his eyes wide. Next to him, in the front passenger seat is a blonde man looking deeply concerned.
That man is Trevor Rees-Jones, a former soldier turned private bodyguard who — for more than 20 years — has held the clues to what happened that terrible night.
Less than five minutes after that photo was taken, two of the car's occupants were killed when the speeding Mercedes S280 limo — travelling at more than 100km/h — slammed into the 13th pillar in the tunnel under the Pont d'Alma near the river Seine.
Diana would die later in hospital after a desperate but futile bid to save her life.
The only person to survive the horrifying smash was Mr Rees, a bodyguard for the Al-Fayed family. (He now only goes by the name Trevor Rees.)
However, despite being the only one of that group still alive, Mr Rees's life since then has been marred by pain, divorce, war and dogged by conspiracy theories about who was really to blame for the death of the People's Princess.
WHO IS TREVOR REES?
Mr Rees served in the parachute regiment and then did a tour in Northern Ireland before leaving the armed forces. In 1995, he went to work for billionaire Egyptian Mohammed Al-Fayed, whose vast empire (then) included Harrods, the Ritz Hotel in Paris and Fulham Football Club.
In the summer of 1997, some biographers have claimed, one of the things that attracted Diana to holidaying with the Al-Fayeds in the south of France (where she met Dodi) was his large private security team. (Diana only used police protection when she undertook official events.)
WHY REES WAS IN THE CAR
Throughout July and August of that year, Diana and Dodi's relationship blossomed in full view of the paparazzi. By August 30, the duo were returning from their third holiday together having cruised around Sardinia. In the afternoon, they had flown to Paris where they initially travelled to the Ritz and then to Dodi's luxury apartment near the Champs-Elysees. Later, they returned to the Ritz. Accompanying them were bodyguards Rees and Kez Wingfield.
With Dodi increasingly stressed by the 30 or so paparazzi chasing them in Paris, the Ritz's deputy security head Henri Paul concocted a plan. The two cars the group had been travelling in that day would leave from the front of the hotel, serving as decoys, while Paul would personally drive the Princess and Dodi in one of the hotel's limos, leaving from the rear entrance.
Rees later told an official British inquest into Diana's death that he was immediately concerned about Paul's plan.
"I wasn't happy as it meant Dodi would be splitting the security officers, but I went along with it," he said. "I advised Dodi that we could leave from the front of the hotel in two vehicles, as the crowd and the press would be pushed back across the road at the front of the hotel. Initially, I had been told that Dodi and Diana would travel without security and I said this would not happen, that I would travel in the vehicle with them."
THE MISSING FOUR MINUTES
Rees would later say the last thing he remembered was climbing into the car at the Ritz, meaning there was a "missing" four minutes from his memory.
In an interview in 2000 he reflected: "I'm the only person who can tell people for real, and I can't remember. It will be so easy if I do remember. I can tell people and all this c**p will finish." (The "c**p" being conspiracy theories about the events of that night.)
Less than five minutes after leaving the hotel, the crash happened. Rees' injuries were catastrophic. He suffered severe brain and chest trauma, spent 10 days in a coma and every bone in his face was broken. Surgeons literally rebuilt his face using old photos as a guide and 150 pieces of titanium. Part of the back of his skull was used to rebuild his cheekbones.
Speaking in a TV interview in 2000, surgeon Luc Chikhani said he had never seen someone still alive who had so many broken bones.
"The face was completely smashed with many different fractures — it was amazingly crushed," Dr Chikhani said. "The face was completely flat. We had to completely rebuild it. The eyes were apart, the nose was smashed and the jaw was broken."
His mother Gill said at the time: "His face looked like it had been hit by a frying pan in a Tom and Jerry cartoon — smashed back and flattened."
MOVING IN WITH MUM
The following year, Mr Rees left Mr Al-Fayed's employ after the grieving father, who believed British security services were behind the crash, asked him to hand control of his dealings with French authorities over to his team. According to the Telegraph, Mr Al-Fayed then said "you betrayed me" and blamed Rees for his "disloyalty". (Mr Rees later alleged Mr Al-Fayed had put "intense" pressure on him to recall events from the tragic night.)
Mr Rees then moved back to Shropshire to be looked after by his mum Gill and stepfather, taking a job in a local sports shop. He published T he Bodyguard's Story: Diana, The Crash And The Sole Survivor in 2000 but his whopping $1.8 million advance was largely eaten up by legal fees, stemming from lawsuits involving Mr Al-Fayed in the UK and France.
In 2003, Mr Rees married his second wife, a teacher named Ann Scott. (He had split from his first wife months before the crash.) The couple had daughter Nia in 2006.
Mr Rees later set up shop working as a security consultant. In 2000 he worked with the United Nations in East Timor and later, in 2008, was working in war-torn Iraq where he helped protect foreign workers.
In 2016, Diana's former bodyguard Ken Wharfe claimed his security team would never have let the royal get in the Mercedes that night and laid fault for her death with the bodyguards.
"I am still angry beyond words that this team of 'bodyguards' let her come to harm. Our department had the care of her personal safety for some 15 years: Fayed's crew were in charge of her security for just eight weeks before she died," Mr Wharfe wrote in the Daily Mail2016.
"Rees-Jones was a former soldier who had not received the training necessary to protect a member of the royal family. When he was first appointed by the Fayed family to guard Diana in France, Scotland Yard could have informally provided Rees-Jones with a briefing.
"The primary role of a protection officer is to use intelligence, their contacts and their instincts to keep their charge out of harm's way by avoiding confrontation.
"A case in point is Rees-Jones's lack of understanding of the paparazzi. He appeared to think in terms of his army days, describing the press as 'the enemy' and referring to photographers as if they were 'snipers' with their long lenses like rifle barrels."
THE TRUTH COMES OUT
In 2008, a British inquest was finally held into the death of Diana, and Mr Rees shared what he could recall of the terrible night, saying: "I have a memory of stopping at traffic lights and seeing a motorcycle on the right hand side of the car. I'm not sure about the other vehicles, but I can remember this motorcycle very clearly.
"My memory then is of total confusion. I don't remember the pain but in my head there was a lot of confusion.
"I don't remember if someone was holding me or attempting to give me treatment.
"I remember having heard somebody moaning and the name Dodi was uttered, but I don't know who said it. On the other hand, if there was no-one else there apart from us, I conclude that it was Princess Diana as it was a female voice."
However, he then cast slight doubt over his own recollections, saying: "These memories are vague and I myself doubt them, but I'm mentioning them as these memories are coming back to me repeatedly."
He also denied Mr Al-Fayed's claims that Dodi was about to propose to Diana and also refuted the allegations that the crash was the work of MI6 agents, saying: "I am not part of a conspiracy to suppress the truth at all. All I have ever done is give the truth as I see it."
FINAL PIECE OF THE PUZZLE
Another key witness at the inquest was Mr Wingfield, the other bodyguard there that night. He testified he and Rees had both been travelling with Dodi and Diana for more than a week and knew they were being hounded by the paparazzi. He said they had asked Mohammed Al-Fayed for more guards to help deal with the situation. He also claimed Dodi would not tell his security team about his plans.
Mr Wingfield said he and Mr Rees had struggled during Dodi and Diana's cruise, working 18-hour shifts to try and protect the duo.
A lingering question hanging over the tragic events of Paris is why Paul, whose autopsy found he was three times more than the legal blood alcohol level, had been allowed behind the wheel that night.
"People say, 'You should have known', but there was nothing in Henri Paul's demeanour that he had been drinking, and Henri Paul wasn't my focus of attention," Mr Wingfield said. "My focus of attention was getting a sandwich down my neck as soon as possible and getting back on the job."
During his evidence, Mr Wingfield told Mr Fayed's barrister Michael Mansfield QC: "If we were allowed to have done our jobs properly by the organisation we wouldn't be having this conversation now."