LOS ANGELES, NOV. 12 -- Actor River Phoenix died from an overdose of cocaine and heroin, the Los Angeles Coroner's Office announced today, and sheriff's detectives are calling the death accidental.

The results of toxicology tests of blood came nearly two weeks after the 23-year-old star collapsed and died after leaving a Sunset Boulevard nightclub in the early morning hours of Oct. 31. The report said the actor died of "an acute multiple drug intoxication" and that "lethal levels" of cocaine and heroin were found in his body. In addition, the report said there were traces of Valium, marijuana and ephedrine, a drug contained in over-the-counter cold medications. No alcohol was found in the body. Coroner's spokesman Scott Carrier said he had no information about how the drugs were ingested, but an official familiar with the autopsy said that drugs were not found in the actor's stomach and that there were no signs of track marks on his body. "It looks like it was snorted," he said.

The official results confirmed the suspicions of law enforcement personnel and the worst fears voiced this week by some of Phoenix's close friends and business associates. Sgt. Mike Lee of the sheriff's department said this week murder charges could be brought if the supplier was ever found.

"Even if Phoenix took {the cocaine and heroin} voluntarily, the person who supplied the drugs would be the target of a second-degree murder case," he said.

"It will be a matter of if people come forward and do the right thing," Lee said about the possible success of his investigation. "But for some reason, in these situations people who know often turn around and defend the person who supplied it. Because they just want it to go away."

More than 10 years after comedian John Belushi died in a bungalow off Sunset Boulevard from a cocaine and heroin overdose -- a death that led to soul-searching in the movie community and, later, a prison sentence for the woman who supplied Belushi with the drugs -- the demise of River Phoenix suggests that little has changed in Hollywood.

"I could only surmise what everyone else could surmise," his publicist, Sue Patricola, said a few days ago. "People talk about him having such a clean life. I think that's not right. ... He was not into killing things, not for food, not for clothes. But that was it. ... He didn't die from carrot juice.

"This place, Los Angeles, is poison, especially for someone who's grown up in an isolated part of the world -- in an idealistic world -- and then comes here. This place is too much. We're a town of excess."

Phoenix's agent, Iris Burton, who had handled his career for 13 years, lamented his death during an interview from her office this week. Burton, who specializes in child actors, railed against the Hollywood forces that tempt -- and occasionally destroy -- "someone so beautiful."

"I don't know what changes them," Burton said. "Even I wasn't aware. Do you think I didn't love this boy? I thought he was acting funny, but I thought that was part of being an actor. ...

"They're trying to make it sound like it's an accident. The first time around. Do you believe that?" she asked pointedly.

News of Phoenix's death, at first, prompted a wave of denial in Hollywood. Friends who were with him the night he died outside the Viper Room, the club owned in part by actor Johnny Depp, said the next day they couldn't talk or they hadn't known the actor that well. Those who would discuss him spoke vaguely only of his goodness.

Top actors and directors who had worked with Phoenix released prepared statements insisting that drugs were anathema to the Phoenix they knew. Businessmen involved with "Dark Blood," the movie Phoenix was working on at the time of his death, would not discuss insurance bonds -- and scoffed at the possibility that the film could be left without coverage if the actor's death was drug-related. (Producer Nik Powell, who had indicated last week that "with ... many major scenes to be shot," it would be virtually impossible to finish the picture without Phoenix, said today in London that the production would "likely fold" within a matter of days.)

This is a town where a newcomer can quickly find out the price of a hit of heroin ($25) or a gram of Special K, an animal tranquilizer that acts like a lightweight PCP ($150), but friends and colleagues of Phoenix's insisted they had never known him to use drugs.

When an autopsy ruled out the possibility of natural causes, however, the Hollywood spin machine began sputtering.

Phoenix, considered one of the most gifted young actors in movies, seemed to have been familiar with all aspects of the Hollywood scene. And interviews with sheriff's detectives, county paramedics, workers at Hotel Nikko, where the young actor was staying, and people who saw him at the Viper Room the night he died indicated that the last day of River Phoenix's life was not particularly unusual or special.

It just ended particularly badly.

Phoenix had just returned to Los Angeles from Utah, where he had been shooting scenes for "Dark Blood." He had worked a 12-hour day on that set. He was staying in a $440-a-night room at the Nikko, which offers 24-hour room service that features vegetarian cuisine. He spent most of the evening at the hotel, and sometime near midnight, he showed up at the Viper Room with his brother Joaquin, who goes by the name of Leaf; his sister Rainbow; and his girlfriend, Samantha Mathis.

People at the club at first didn't recognize the young star. He had cut and dyed his blond hair dark for his latest movie role. After his collapse about an hour later, Mathis and Leaf Phoenix helped him out of the club and laid him on a sidewalk, but few passersby recognized the stricken actor.

One who did was celebrity photographer Ron Davis, who first noticed Mathis as she exited the club with Phoenix on her shoulder. Phoenix, he said, "looked liquid. He was gone when they walked out with him. Then they laid him out on the sidewalk and he began having a really violent series of seizures." Davis estimated Phoenix convulsed for about 25 minutes before his brother ran to a pay phone to call 911. Phoenix had no pulse and was not breathing when paramedics arrived, said Capt. Ray Ribar, who was at the scene.

The paramedics asked people around Phoenix whether the actor had taken any drugs. Paramedics were told he had taken cocaine and Valium before he became ill, sheriff's deputies said. Ribar later was quoted as saying the actor displayed symptoms of "a classic cocaine overdose." Ribar said paramedics gave Phoenix three substances to combat his problems: epinephrine, to start the heart; a mixture of dextrose and water for fluids; and Narcan, a drug to reverse the effects of opiates in his system. During the entire procedure, on the sidewalk and later, as the ambulance drove to Cedars-Sinai Medical Center, Phoenix did not respond.

"He was clinically dead when we got to the club," Ribar said.