Mr. Azerrad, who last spoke to Mr. Cobain in January, said the musician became a heroin addict, in part, because of a persistent and unexplained stomach ailment.

"He was also in a fair amount of psychic pain," said Mr. Azerrad. "He was a very sensitive person, sweet and bright, which are not the best qualities to have if you are a rock star."

Nirvana's last album, "In Utero," was released last year to critical acclaim and large sales. Mr. Cobain reproached his own fame in songs he wrote for the album, singing "I do not want what I have got" and "What's wrong with me?"

Founded in 1986, Nirvana, which included Christ Novoselic on bass and Dave Grohl on drums, produced its first album, "Bleach," in 1990 on the Seattle-based Sub Pop label. "Bleach" was recorded for $606 and initially sold 30,000 copies, respectable for an independent label but tiny by commercial standards. The album helped the group establish a strong following on the college circuit with loud live shows that sometimes ended with bouts of equipment smashing.

The band recorded its later albums with Geffen Records. The company's president, Ed Rosenblatt, said, "We are all devastated by the unbelievable tragedy of Kurt Cobain's death."

The band's success, coming out of small clubs in a distant corner of the country, helped to clear the path for other Seattle bands like Pearl Jam and Soundgarden. Complaints About Fame

After he became famous, Mr. Cobain frequently complained about his own success. "I do not want to have a long career if I have to put up with the same stuff that I'm putting up with," Mr. Cobain said in an interview with The New York Times last November. "I'm trying it one last time, and if it's more of a pleasant year for us, then fine, we'll have a career. But I'm not going to subject myself to being stuck in an apartment building for the next 10 years and being afraid to go out-side of my house. It's not worth it."