LOS ANGELES (AP) _ An autopsy on Olympic sprinter Florence Griffith Joyner did not immediately determine the cause of death, a sheriff's spokesman said today.

``It could take a few days or a few weeks'' before a cause is determined, said Lt. Hector Rivera of the Orange County Sheriff's Department. Rivera said the coroner started the autopsy Monday at 1 p.m., but didn't know how long the procedure took.

The coroner conducted a series of standard tests, including toxicology, done when the cause of death is unknown, Rivera said.

The 38-year-old athlete, famed for her speed and stylishness, died early Monday at her Mission Viejo home. She had suffered from heart problems in recent years.

Her husband, Al Joyner, the 1984 Olympic triple jump champion, called authorities after finding her ``unresponsive and not breathing,'' Rivera said. ``She died in her sleep sometime during the night,'' he said.

A decade ago this week, Griffith Joyner won three gold medals at the Seoul Olympics, where her sister-in-law, six-time Olympic medalist and world heptathlon record-holder Jackie Joyner-Kersee, also starred. In an NBC interview today, Joyner-Kersee praised her as ``a woman of substance.''

Griffith Joyner, or FloJo, as she was known, still holds world records in the 100- and 200-meter dashes. She set the 100 mark of 10.49 seconds in the quarterfinals of the 1988 Olympic trials at Indianapolis, and since then, no one has even broken 10.60. At Seoul, she won the gold medal in a wind-aided 10.54.

Griffith Joyner then smashed the world 200 record in the Olympic final, clocking 21.34. American Marion Jones, with a 21.62 at the World Cup in South Africa this month, is the only other woman to run the 200 in under 21.70.

Griffith Joyner also won a gold medal in the 400 relay and just missed a fourth gold medal when the U.S. team finished second in the 1,600 relay, which Griffith Joyner anchored.

``It's an amazing legacy. Many have tried and all have failed in terms of her records,'' said nine-time Olympic gold medalist Carl Lewis. ``(Her death) is something that impacts the sport when the sport is hurting very, very bad.''

Track and field had never produced such an exotic creature. At the 1988 trials, she stunned fans and competitors by running in a purple bodysuit with a turquoise bikini brief over it, but nothing on her left leg.

``She proved a beautiful woman could go out and be a phenomenal athlete,'' said Dwight Stones, a two-time Olympic bronze medalist in the high jump. ``We won't know for a long time how many female athletes she inspired by being her own person.''

At the Olympics, she painted three of her fingernails red, white and blue, and she painted a fourth gold to signify her goal.

At the 1987 World Championships in Rome, Griffith Joyner caused a sensation by running the first two rounds in a skintight suit similar to a speedskater's togs.

``What Florence brought to track was a flash and a flair that we didn't have, which was probably good for the sport and got attention for us,'' said Olympic gold medalist Evelyn Ashford, her chief rival in the early '80s.

Griffith Joyner's muscular physique prompted talk of steroid use, but she insisted she never used performance enhancers and she never failed a drug test.

``She was very, very determined,'' said Jeanette Bolden, a former Olympic teammate and head women's track and field coach at UCLA. ``There was no impossibility to anything. She really tried to live that.''

Primo Nebiolo, the head of track's international federation, said he knew Griffith Joyner had ``some serious heart problems in recent months,'' although one of her brothers, Weldon Pitts, said she had shown no sign of illness recently.

Griffith Joyner suffered a seizure two years ago on a flight from California to St. Louis, and was hospitalized for one day. Her family did not disclose the ailment.

Griffith Joyner was born Dec. 21, 1959, in the poor Watts section of Los Angeles, one of 11 children of an electrical technician and a teacher.

At David Starr Jordan High School in the late 1970s, she was a studious athlete obsessed with the 100-meter dash.

``She just flowed, like she wasn't even running hard,'' said Will Burnett, a classmate and now football coach at Jordan. ``I used to race against her and she smoked me. She ate me up.''

She graduated from high school in 1978, attended Cal State Northridge for two years, then graduated from UCLA in 1983 with a degree in psychology.

In 1987, she married Al Joyner, who would become her coach. They have a 7-year-old daughter, Mary Ruth.

After retiring from track after the Seoul Games, she wrote children's books and poems; she was a beautician, an artist, a model and a clothes designer; she performed in movies and television; she designed the uniforms for the Indiana Pacers basketball team.

She also served as co-chair of the President's Council on Physical Fitness and Sports.

``What exactly is a role model? Is it someone that is trying to set positive examples for kids?'' she told The Associated Press in 1994. ``Then that's what I'm trying to do. I'm very happy to have that title.''

Joyner-Kersee said this morning on ``Today'' that her sister-in-law, even when tired, always found time ``to put a smile on a young person's face.''

``She accomplished amazing things on the track as well as off the track,'' Joyner-Kersee said. ``Florence was a woman of substance.''

Griffith Joyner tried a comeback before the 1996 Olympics in Atlanta, but problems with her right Achilles' tendon forced her to abandon the attempt.

``It's been hard for me. All the training I've done, I've never had problems with my Achilles,'' she said at the time. ``My husband tells me I'm getting older. I tell him to shut up.''