Two years after Michael Jackson's shock death, the mystery over exactly how he died continues to fuel legal wrangling, conspiracy theories and family strains over the King of Pop's clouded legacy.

While fans are expected to pay their respects this weekend — including by dropping red roses from the air over his famous Neverland ranch – many questions remain over his death on June 25, 2009 aged only 50.

His personal doctor Conrad Murray is still awaiting trial on manslaughter charges for allegedly giving Jackson an overdose of powerful sedative propofol to help him sleep on the fateful morning at his Beverly Hills mansion.

The trial was to have started in May, but has been delayed until September after his defence lawyers – expected to argue that Jackson effectively killed himself – said they need more time to prepare.

Days ahead of the second anniversary of his death, Michael Jackson's sister La Toya published a new book reiterating her claim that he could have been murdered, and had voiced fears to her that he would be for financial reasons.

"I truly feel Dr Murray was simply the fall guy. I think it's too easy to blame him. I think the investigation needs to go a bit further than just stopping at Dr Murray," she said ahead of the book's publication this week.

"There are a lot of other people that are involved in this. My brother told me," she said, while declining to elaborate.

Many of the lurid details of what happened on the day Jackson died have emerged in legal wranglings over the last two years to prepare for his doctor's trial.

The controversial singer – preparing for a series of comeback concerts in London, four years after being acquitted on child sex abuse charges – was being treated for chronic insomnia including by using propofol.

The trial will centre on the suggestion that Dr Murray mistakenly administered a fatal overdose, and failed to notice in time because he was busy on the phone with a series of female friends.

The defence will reportedly argue that Michael Jackson could have administered an extra dose of propofol by himself, while Dr Murray was out of the room, effectively provoking his own death.

Whatever the outcome of the trial , expected to be watched closely by Michael Jackson's millions of fans around the world, it will likely only fuel publicity for the multi-million-dollar industry based on the performer's legacy.

The official part of that legacy is managed by his executors, lawyer John Branca and accountant John McClain, named in the late singer's will, which also appointed his mother Katherine as guardian of his three children.

The estate – which controls Michael Jackson's huge music catalogue – for example was behind the December release of Michael, the first of what could be several posthumous albums based on material Michael Jackson recorded before his death.

A Michael Jackson video game has been a huge hit, while in April it teamed up with Canadian dance-based troupe Cirque du Soleil to announce a series of shows inspired by Jackson's music and dance, including a permanent one in Las Vegas.

His brother Jermaine this week launched a Michael Jackson exhibit at Madame Tussauds waxwork museum in Hollywood, including three Jackson figures from various stages of his career.

But other members of Michael Jackson's notoriously idiosyncratic family have launched a number of project over the last two years, including a 2009 tribute concert that had to be postponed after a number of stars pulled out.

One recent such deal was between his father Joe and a French parfumier for a Jackson branded scent. Its launch this month descended into chaos after a lawsuit was filed by Bravado, the company which holds the commercial rights to Michael Jackson's name, seeking compensation for every bottle sold.

The smell should be better this weekend, when Michael Jackson fans will drop roses over Jackson's former Neverland ranch, during memorial flights offered by a local helicopter company to mark the second anniversary.

The Michael Jackson estate has not organised anything official to commemorate the date this year, in contrast to the first anniversary last year, although it has not ruled out making a short statement on the day.