Police have stepped up their investigation into the death of Michael Jackson, removing bags of medications from his home as his mother was awarded temporary custody of his three children.

The family fired the first shots in the legal battle to take control of his personal and financial affairs, asking a judge to name Katherine Jackson as administrator of his estate.

They made it clear they believed they should take charge of both his debt-ridden but potentially lucrative financial empire and act as permanent caretakers of his three children. The family wants to avoid large numbers of people claiming to act in Michael Jackson's interests.

In documents filed in Superior Court, Jackson's parents said they believed their 50-year-old son died without a valid will, despite reports that a will made in 2002 exists. That will is said to divide the estate between the singer's mother, three children and one or more charities but does not leave anything to his father, Joe Jackson.

In the documents Burt Levitch, an attorney for Mrs Jackson stated that others hold documents, including a will, that could work "to the detriment of the estate".

Judge Mitchell Beckloff granted Mrs Jackson, 79, temporary guardianship of Michael Joseph Jackson Jr., known as Prince Michael, 12, Paris Michael Katherine Jackson, 11, and Prince Michael II, 7. The court documents state that she intends to use her late son’s assets exclusively for his children “after payment of debts and expenses of administration”.

The judge did not immediately rule on her requests to take charge of the children's and Jackson's estates, including his stake in the massive Sony-ATV Music Publishing Catalog estimated to be worth as much as $2 billion. He scheduled a hearing for July 6 and another for August 3 to consider those issues and whether Mrs Jackson should be appointed the children's permanent guardian.

The judge later on Monday also granted Mrs Jackson the right to take control of her son's personal property after she expressed concerns about who controls his business ventures and bank accounts.

Londell McMillan, the family's attorney, said in a statement that the Jacksons were pleased with the results.

"Mrs Jackson deserves custody, and the family should have the administration of the brilliance of Mr Michael Jackson. Mrs Jackson is a wonderful, loving and strong woman with a special family many of us have admired for years. The personal and legal priorities are focused on first protecting the best interests of Mr Michael Jackson's children, his family, his memorial services and then preserving his creative and business legacy with the dignity and honour it deserves," he said.

Investigators retrieved medications from the rented mansion where pop star collapsed last week. Two coroner's investigators and two police detectives spent several hours inside the three-story house and emerged with two large red bags filled with evidence.

The coroner's office performed a post-mortem examination on the 50-year-old singer's body on Friday but deferred a decision on the cause of death, ordering toxicology tests. A second, private autopsy has been requested by the family, over concern about his final hours.

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