Stars have been celebrating the life of Michael Jackson in Los Angeles.Jackson's father Joe joined celebrities at the annual Black Entertainment Television (BET) Awards show, which was hastily changed to honour the singer.It is the first big tribute to Jackson, who collapsed and died last week in the city at the age of 50.His family insisted a second autopsy be carried out on his body because of what they said were "unanswered questions" over how he died.Speaking on the red carpet, Joe Jackson said he had "a lot of concerns" over events surrounding his son's death.The Los Angeles County Coroner's office has ruled out foul play but deferred giving a cause of death until the results of toxicology tests come back.Unconfirmed reports suggest the singer had been taking a daily dose of Demerol, a painkiller also widely known as pethidine.On Saturday police carried out what they said was an extensive interview with Jackson's personal doctor, Conrad Murray, who was with the singer when he died.A spokeswoman for Dr Murray said he was not a suspect in the case. He had "helped identify the circumstances around the death of the pop icon and clarified some inconsistencies", she said.'Celebrate this man'The BET awards show was turned into a tribute to Jackson, with major stars re-working their performances in honour of the singer.A Jackson 5 medley was performed and host Jamie Foxx attempted the Moonwalk."No need to be sad. We want to celebrate this black man ... We gonna go through all of Michael Jackson," he said.Winners praised Jackson as they received their awards."We all know none of us in this in this room wouldn't be here for Michael Jackson," said Lil Wayne, named best male hip-hop star.Late in the show Jackson's sister Janet took the stage to thank fans for their support."My entire family wanted to be here tonight, but it was just too painful, so they elected me to be here," she said.Demand for Jackson's music has surged since his death on Thursday, with the star dominating sales at music retailers and download sites across the world.On Sunday his songs topped Apple's iTunes download charts in every country except Japan.In the UK Jackson scored a posthumous number one album with greatest hits compilation Number Ones, with four other albums reappearing in the top 20.In the singles chart, 43 out of the top 200 singles featured the singer, with Jackson hits accounting for all but one of the new entries in the top 40.Source: BBC