Police investigating Michael Jackson's death were looking for one of the pop king's doctors after seizing a car that they said may contain drugs or other evidence. As medical examiners began an autopsy for Jackson, police towed a BMW from rented home “because it may contain medications or other evidence that may assist the coroner in determining the cause of death,” police spokeswoman Karen Rayner said. She said the car belongs to one of Jackson's doctors whom police wanted to interview. Rayner said she did not know the doctor's identity and stressed the doctor was not under criminal investigation. The autopsy began Friday morning and was expected to last several hours. An official determination on the cause of death was not expected for weeks or longer, until more sophisticated tests are completed. As stores reported they were inundated with orders for Jackson's music, a chorus of grief for the megastar spread around the world, from statesmen to icons of music to legions of heartbroken fans. “I can't stop crying. This is too sudden and shocking,” said Diana Ross, who helped launch Jackson's career. “I am unable to imagine this. My heart is hurting.” The White House also weighed in for the first time, with a spokesman saying President Barack Obama saw Jackson as a spectacular performer and music icon whose life nonetheless had sad and tragic aspects. The House of Representatives observed a moment of silence. Brian Oxman, a former Jackson attorney and a family friend, said Friday he had been concerned about Jackson's use of painkillers and had warned the singer's family about possible abuse. “I said one day, we're going to have this experience. And when Anna Nicole Smith passed away, I said we cannot have this kind of thing with Michael Jackson,” Oxman said on NBC's “Today” show. “The result was, I warned everyone, and lo and behold, here we are. I don't know what caused his death. But I feared this day, and here we are.” Oxman claimed Jackson had prescription drugs at his disposal to help with pain suffered when he broke his leg after he fell off a stage and for broken vertebrae in his back. After Jackson was acquitted on child molestation charges in 2005, prosecutors argued against returning to Jackson items including syringes, the drug Demerol and prescriptions for various drugs, mainly antibiotics, in different people's names.