One month on, questions swirl around Jackson

His cause of death remains unknown, the whereabouts of his body is a mystery, the fate of his estate and children are uncertain and conspiracy theories abound.

Almost one month after Michael Jackson collapsed and died at his rented Los Angeles chateau on June 25, the tragic King of Pop's demise continues to raise more questions than answers.

In the clearest sign yet that authorities may be zeroing in on what caused the 50-year-old superstar's death, federal agents and police on Wednesday raided the Houston offices of Mr Jackson's doctor Conrad Murray.

A lawyer for Dr Murray, who has already been interviewed twice by police, said detectives executed a search warrant seeking evidence of "the offense of manslaughter," indicating Jackson's death is now being treated as a crime.

Dr Murray, hired by Mr Jackson in May to help him prepare for his gruelling series of comeback concerts, has been the subject of intense speculation as he was the last person to see the star alive.

Yet Dr Murray's lawyers are adamant that the 51-year-old cardiologist is innocent of any criminal wrongdoing.

"Based on Dr Murray's minute-by-minute and item-by-item description of Mr Jackson's last days, he should not be a target of criminal charges," attorney Ed Chernoff said in a statement.

Investigators are reportedly focusing on the role of a powerful sedative, Diprivan, found at Mr Jackson's home after his death.

Experts say the drug, used in hospitals to induce unconsciousness in patients before major surgery, should only be administered by an anaesthesiologist and should never be used at home.

Whether Diprivan was present in Mr Jackson's body at the time of his death has not been revealed. Investigators from the Los Angeles County Coroner's office say they are still awaiting the results of toxicology tests carried out at a post mortem on June 26.

A cause of death has been deferred pending the results. The absence of an official cause of death has only served to fuel the feverish speculation about what killed the pop idol. The singer's sister La Toya told a British newspaper - for an undisclosed sum - that she believed he had been killed by a shadowy conspiracy.

"Michael was murdered. And we don't think just one person was involved ... I feel it was all about money," she said.

The value of Mr Jackson's own music has sky-rocketed since his death, with his solo album sales topping more than 2.3 million.

The heirs to the Jackson estate, his children Prince Michael, 12, Paris, 11, and younger brother Prince Michael II, 7, are in the care of Katherine Jackson, named in the singer's will as their legal guardian.

However the biological mother of Prince and Paris, Mr Jackson's ex-wife Debbie Rowe, is reportedly mulling whether to seek custody of the children.

Lawyers for Katherine Jackson and Ms Rowe are due to appear in court August 3 after postponing three earlier hearings.