An early-morning traffic accident in a Paris tunnel killed Diana's companion, Dodi Al-Fayed, and the driver of their car. But Diana was conscious after the accident and did not appear to be seriously hurt. In truth, she was bleeding internally.
Had the accident occurred in the United States, Diana would have been rushed to a hospital. However, the French have a different system: They first try to stabilize the patient at the scene. Still, as CBS News correspondent Erin Moriarty reports, that difference doesn't explain the series of missteps and delays in Diana's medical care that experts say never should have happened.
"My first reaction was this is not what should be expected of emergency medical services for anybody in this type of circumstance," says Chicago's Dr. Stanley Zydlo, a pioneer of emergency medical care in the U.S.
Zydlo and three other emergency medicine specialists analyzed a 40-page French accident report obtained by CBS News. All four agreed that mistakes were made.
"Yes, with hindsight, they probably would have done it differently, I suspect," says Dr. Annie McGuinness of London.
Diana: Remembering A Princess
At 12:32 a.m. on Aug. 31, 1997, rescue workers arriving at the scene find Diana conscious, but agitated.
At 12:45 a.m., a French doctor arrives. Not initially recognizing the extent of her injuries, he gives Diana Hypnovel and Fentanyl - a combination of drugs that calmed her down, but is also known to sometimes cause heart and respiratory problems.
"Do you believe that these sedatives could actually have aggravated her situation?" asks Moriarty.
"The word is 'could have.' Yes, they could have," says Zydlo.
Time is lost as rescuers remove an already dead Al-Fayed from the car first.
When emergency workers ask to take Diana to a hospital just four miles away, it takes another 10 minutes for the hospital to agree. It is now 1:29 a.m.
"They should have had a receiving hospital before they were ready to leave the scene, given that they had already spent nearly an hour on the scene," says McGuinness.
Even more time is lost as the doctor orders the ambulance to drive slowly for fear of aggravating Diana's condition.
The result: Diana doesn't arrive at the hospital until 2:06 a.m. - nearly two hours after the accident.
All told, Zydlo estimates 70 minutes were lost by bad decisions.
How crucial is that time in an injury like Diana's?
"Anybody that's bleeding has to have the bleeding stopped as soon as possible," Zydlo said.
Diana is pronounced dead at 4 a.m.
Could she have been saved?
McGuinness believes Diana was too badly injured. Zydlo says we'll never know.
"I can't say she definitely would have survived, but it certainly took away all of her chances," Zydlo said.
No official from the French emergency system would comment on Princess Diana's treatment for this report - but in 2002, five years after her accident, the French emergency guidelines were changed. Today, a patient with the same the unstable blood pressure would be rushed to a hospital.