Arnie Klein, a doctor best known for treating the late Michael Jackson, has died at the age of 70. Klein was not only Jackson’s longtime physician, but they were close friends as well.

Klein died of natural causes on Thursday night in Palm Springs, Calif. He checked into the hospital days ago, complaining of abdominal pain.

According to TMZ, Klein’s career and livelihood went downhill after Jackson’s death in 2009. He was once a dermatologist to the stars, but after allegations that he had administered drugs, like Demerol and Propofol, to Jackson dozens of times in the weeks leading up to his death, his career was essentially over.

He was also accused of prescribing Jackson drugs under various aliases. In 2013 he filed for bankruptcy and was arrested after he failed to show up in bankruptcy court.

Klein was so close with Jackson, in fact, that there are rumors he might be the biological son of the “Thriller” singer’s son Prince.

The Mirror reports Prince ironically admitted he might not be the biological child of Jackson in a tweet earlier this month, writing, “The blood of the covenant is thicker than the water of the womb' I was raised by my dad with my brother and sister."