France closed the books today on its investigation into the car crash that killed Princess Diana, her friend Dodi Fayed and their driver Henri Paul two years ago.

Investigating magistrates Herve Stephan and Marie-Christine Devidal dropped manslaughter and negligence charges against nine photographers and one motorcycle driver who were chasing the Mercedes carrying Diana when it hit a pylon in a Paris underpass. The two investigators said the accident was not "a voluntary act" by anyone.

The accident, they wrote, was due to the fact that Paul "was in a state of drunkenness, and under medications incompatible with alcohol."

Paul's impairment, they said, "did not permit him to master his vehicle while driving at a rapid speed in a difficult stretch of roadway, and having moreover to avoid another vehicle going in the same direction but at a slower speed."

A Paris prosecutor charged with the case, Maud Coujard, said as much in her recommendation to the investigating magistrates two weeks ago.

According to reconstructions of what happened a few minutes after midnight on Aug. 31, 1997, the Mercedes carrying the Princess of Wales was being chased by paparazzi in cars and on motorcycles from the moment it left the Ritz Hotel and turned down a Seine riverbank roadway.

As it entered the short tunnel under the Place de l'Alma at 100 mph, the Mercedes S-280 came upon a slow-moving Fiat Uno, swerved to avoid it, struck the unprotected pylon and bounced against the outer wall before coming to a rest. Pursuing photographers, seconds behind, were on the scene immediately.

The driver and possible passengers of the Fiat, who might have offered clues about the accident, were never found despite a nationwide hunt for the car.

The fourth occupant of the Mercedes, bodyguard Trevor Rees Jones, recovered from severe injuries and is living in Britain. He has threatened to file charges against the Ritz and the car-leasing agency for "endangering the lives of others" by putting Paul at the wheel.

Paul, an assistant security director of the Ritz Hotel, was off duty when he was pressed into service. He had been drinking--according to the post-mortem tests, he'd had the equivalent of nine alcoholic drinks--and had been taking anti-depressants and other medications. Paul also wasn't licensed to carry passengers in the Mercedes, and he wasn't used to high-speed flight from paparazzi.

Yet Stephan and Devidal said Fayed's decision to enlist Paul to drive the car "could not be reproached."

Even so, Fayed's father, Ritz Hotel owner Mohammed Fayed, repeated today that he would appeal the decision, maintaining, according to one of his spokesmen, Laurie Mayer, that "if there had been no chase, there would have been no crash." In France, a decision to drop charges is almost never reversed.

Mohammed Fayed is the most prominent of those who believe the crash could have been part of a plot to prevent his son, a Muslim, from marrying Diana. There is no evidence that Diana planned to marry Dodi.

The investigating magistrates did, however, reproach the nine photographers and the motorcycle driver for snapping pictures of the dazed Diana--she was pronounced dead at a hospital at 4 a.m.--and the other victims in the moments after the crash.

That response was "unanimously and severely condemned" by eyewitnesses on the scene, the magistrates noted. The photographers' actions, said Stephan and Devidal, raise "ethical and moral" questions for them and their employers--photo agencies and client magazines--but do not constitute any kind of criminal infraction.

The men had been under investigation for nearly two years for involuntary homicide and for failure to assist endangered persons--namely, Diana.

Spokesmen for the British royal family declined to comment on the end of the investigation, but Diana's brother, Earl Spencer, thanked the French authorities, saying, "I respect the legal conclusions that have been reached."

CAPTION: Friday, outside Harrod's in London, cards and flowers pile up in tribute to Princess Diana.