The Los Angeles County coroner has opened an investigation into the death of Hollywood legend Marlon Brando's eldest son, acting at the request of his family, a spokesman for the medical examiner said on Tuesday.

Medical examiners took custody of Christian Brando's body on Monday and performed an autopsy on Tuesday, but a finding on the cause of death will await toxicology tests that take six to eight weeks to complete, said Ed Winter, assistant chief of the coroner's office.

Brando, the troubled son of the late Oscar-winning screen star and Welsh actress Anna Kashfi, died early on Saturday at age 49, at a Los Angeles hospital where he was being treated for pneumonia, according to lawyers for his father's estate.

Winter said Brando's family was concerned about his prior history, both medical and drug history, but I'm not going to go any further into it until we have a chance to look at it and do our investigation.

Brando's ex-wife, Deborah, was quoted in a weekend story on People magazine's Web site as saying her former spouse had been comatose and on a respirator before his death. His body was totally compromised, she said. He lived so hard. ... This is just so sad.

An attorney for Marlon Brando's estate, David Seeley, told Reuters it was Kashfi, Christian's long-estranged mother, who asked for a coroner's investigation.

Neither the estate of Marlon Brando, nor its beneficiaries, are involved in these decisions, Seeley said. At this point we have no reason to question the hospital's actions or the cause of death as previously stated, he added.

The autopsy came a day after Deborah Brando, who has claimed in the past to be the illegitimate child of Elvis Presley, filed suit against the executors of Marlon Brando's will asserting a claim to the actor's estate.

ESTATE SAYS SUIT WITHOUT MERIT

The suit says Christian Brando transferred his rights as a beneficiary of the estate to his ex-wife -- making her an assignee -- under a February 2007 settlement of a domestic abuse case she brought against him after their brief marriage was annulled.

And she claims the executors of the Brando estate forged a codicil to his will days before his 2004 death to prevent anyone from challenging the will or trust.

Seeley said Deborah Brando's lawsuit was without merit.

And attorney Benjamin Brin, who represented Christian Brando in his 2007 settlement with his ex-wife, said their agreement does not make her an assignee of any rights whatsoever.

Instead, Christian Brando agreed to pay her the sum of $45,000, contingent on his receiving future disbursements from his father's estate that have yet to be made, Brin said.

According to Seeley, Christian Brando was one of nine beneficiaries who shared equally in proceeds from his father's personal property -- roughly $2.3 million from the 2005 auction of the actor's furniture, clothing, artwork and other effects.

The will also established a living trust to manage Marlon Brando's remaining assets -- including real estate in Tahiti, residual payments and profit participation from his acting career -- for the benefit of Christian and fellow heirs. But no distribution from that trust has yet been made, Seeley said.

Christian Brando made worldwide headlines in 1990 by shooting dead the boyfriend of his half-sister, Cheyenne, and later served five years in prison for voluntary manslaughter. Cheyenne Brando committed suicide in 1995.

Marlon Brando, considered one of the greatest actors of his generation, died in 2004 at the age of 80.

(Editing by Dan Whitcomb and Todd Easstham)