In a new twist to the controversy surrounding pop star Michael Jackson's death, his sister La Toya has claimed that the King of Pop was murdered for his fortune as "he was worth more dead than alive".

Her claim comes just two days after the chief of Los Angeles police admitted they were investigating Jackson's death as possible homicide.

La Toya said she and the family are convinced her brother's apparent drugs overdose was "foul play" by a shadowy group out to get their hands on his £1 billion fortune, the News of the World reported.

"Michael was murdered. And we don't think just one person was involved. Rather, it was a conspiracy of people. I feel it was all about money. Michael was worth well over a billion pounds in music publishing assets and somebody killed him for that. He was worth more dead than alive," the newspaper quoted La Toya as saying.

The 53-year-old claimed that the pop icon, who died at the age of 50 on June 25, was fed a series of addictive drugs to keep him submissive and controlled.

"Michael had many needle marks on his neck and on his arms, and more about those will emerge in the next few weeks. But nothing has changed my mind that this was murder and I won't give up until I find out what killed my brother," she said.