The Los Angeles coroner's office says it may be weeks before it is known exactly what killed pop star Michael Jackson.
Coroner office spokesman Craig Harvey told reporters late Friday that an autopsy of Jackson's body indicated no signs of external trauma or foul play. But, he says the office is deferring determination on cause of death for now.
Harvey says additional toxicology and pulmonary testing is needed before a determination can be made. He says the tests usually take four to six weeks to complete.
Late Friday, the coroner's office said the body of the international pop star was released to his family.
Meanwhile, Los Angeles police are seeking to question Dr. Conrad Murray. He was with the singer when he died suddenly on Thursday.
Police towed the doctor's car, which was at Jackson's house, and say they are looking for medications that could be related to the death.
Jackson was pronounced dead Thursday at the UCLA Medical Center after suffering cardiac arrest at his Los Angeles home.
White House Spokesman Robert Gibbs said Friday that U.S. President Barack Obama called Jackson a "spectacular performer" and a "music icon," but said the president also noted parts of the singer's life were "sad and tragic."
Jackson died about two months before his 51st birthday, and just before July's scheduled launch of a series of comeback concerts in London. Tickets for his London shows, offered in March, sold out in minutes.
Jackson had been rumored to be in ill health for years, but the promoters of his London shows say he passed a recent medical examination.
The singer, dancer and songwriter became famous as a child in the 1970s while performing with his brothers in The Jackson 5 pop group. He went on to an unprecedented solo career, selling more than 750 million records, including the best-selling albums Off the Wall and Thriller, becoming a dynamic live stage act, and pioneering the music video genre.
Jackson was dogged by controversy in his later years. He was acquitted in a child-molestation trial in 2005 and struggled with financial problems. He was the subject of countless tabloid newspaper stories about his eccentric behavior, close relationship with children and multiple plastic surgeries that led to a dramatic change in his appearance.
Some information for this report was provided by AFP, AP and Reuters.