Celebrity news and gossip site TMZ.com, which broke the story of his sudden death yesterday, reports that Los Angeles police are trying to find Jackson's personal physician, who reportedly gave Jackson an injection before he died.
This would be routine step in an investigation like this, and does not mean the physician is under suspicion of wrongdoing.
3.34pm:
The Guardian's Health Editor Sarah Bosley shows how Jackson's bizarre and complicated globe-trotting lifestyle may have contributed to his ill health and death yesterday.
3.28pm:
The Guardian's Sam Jones reports on Jackson's last hours of life.
At 10pm on Wednesday Michael Jackson arrived at the 20,000-seat Staples Centre arena in downtown Los Angeles to rehearse for a comeback tour that he would not live to embark on.
His band, backing singers and dancers had been kept waiting for three hours to go through the show that was intended to regild his crown as the King of Pop. They saw a thin, listless and lethargic figure take the stage.
Despite his frailty and increasingly fading resemblance to the vigorous showman he had been two decades ago, Jackson practised late into the night. If he was unusually ill or upset, those present at the Staples Centre say they saw no sign of it.
2.59pm: Jackson is said to have died owing anything up to $500m (£302m). His incredible debts are put down to his lavish spending sprees and the huge costs of defending himself against child abuse allegations.
(I'm signing off for the day. Thanks for all your comments. Please keep them coming. Daniel Nasaw in Washington is about to take over.)
2.44pm: Only hours after Jackson's death the great cash in begins. DVD Michael Jackson – The Trial and Triumph of The King of Pop, which was due to be released to coincide with his O2 shows, is being rushed into shops with the press release claiming it is "perhaps even more moving and poignant" since his death
12.46pm: Tributes continue to come in. Paul McCartney called Jackson "the massively talented boy man with a gentle soul." The pair collaborated on tracks in the 1980s, including the hit Say Say Say.
11.59am: Martin Bashir, the journalist made the controversial documentary Living With Michael Jackson, has said the world has lost its "greatest entertainer".
The documentary was a PR disaster for Jackson when he said sharing a bed with a young boy was "a beautiful thing" and was shown holding hands with Gavin Arvizo, a 13-year-old boy who later accused him of child molestation. The singer later said he felt "devastated and utterly betrayed" by the interviewer's portrayal of him.
10.38am: Byron Garcia, who organised the famous video of 1,500 inmates synchronized dancing to Jackon's Thriller at a Philippine prison, said: "My heart is heavy because my idol died." Garcia, a security consultant, said the inmates in Cebu will hold a tribute for Jackson on Saturday with their Thriller dance and a minute of prayer.
9.47am: Despite his troubled life, Jackson will be remembered foremost for his musical legacy. His spectacular concert tours earned him comparisons with Frank Sinatra and Elvis Presley. Clips of his greatest performances have leapt to the top of YouTube's video charts in the wake of his death
