CHANHASSEN, Minn. — Prince Rogers Nelson had an unflinching reputation among those close to him for leading an assiduously clean lifestyle. He ate vegan and preferred to avoid the presence of meat entirely. He was known to eschew alcohol and marijuana, and no one who went on tour with him could indulge either.

But Prince appears to have shielded from even some of his closest friends that he had a problem with pain pills, one that grew so acute that his friends sought urgent medical help from Dr. Howard Kornfeld of California, who specializes in treating people addicted to pain medication.

Dr. Kornfeld, who runs a treatment center in Mill Valley, Calif., sent his son on an overnight flight to meet with Prince at his home to discuss a treatment plan, said William J. Mauzy, a lawyer for the Kornfeld family, during a news conference on Wednesday outside his Minneapolis office.

But he arrived too late.

When the son, Andrew Kornfeld, who works with his father but is not a doctor, arrived in Chanhassen, the Minneapolis suburb where Prince lived, the next morning, he was among those who found the entertainer lifeless in the elevator and called 911, Mr. Mauzy said. Emergency officials arrived but could not revive Prince. He was dead at 57.