In documents filed in Superior Court, Jackson's parents said they believe their 50-year-old son died without a valid will.
They also made it clear they believe they should take charge of both his debt-ridden but potentially lucrative financial empire and act as permanent caretakers of his three children.
Judge Mitchell Beckloff granted 79-year-old temporary guardianship of the children, who range in age from 7 to 12. He did not immediately rule on her requests to take charge of the children's and Jackson's estates.
Beckloff scheduled a hearing for July 6 and another for Aug. 3 to consider those issues and whether Katherine Jackson should be appointed the children's permanent guardian.
The judge later on Monday also granted Katherine Jackson the right to take control of her son's personal property that is now in the hands of an unnamed third party. The ruling does not detail the nature of those items and does not provide control of any money in the estate.
L. Londell McMillan, the family's attorney, said in a statement that the Jacksons are pleased with the results of their Monday filings.
"Mrs. Jackson deserves custody, and the family should have the administration of the brilliance of. 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 honor it deserves."
When Jackson died Thursday, he left behind a 12-year-old son and 11-year-old daughter by his ex-wife Deborah Rowe, as well as a 7-year-old son born to a surrogate mother.
The Jackson family said the children — Michael Joseph Jackson Jr. (known as Prince Michael), Paris Michael Katherine Jackson and Prince Michael II — are living at the Jackson family compound in Los Angeles' San Fernando Valley.
"They have a long established relationship with paternal grandmother and are comfortable in her care," the family said in court documents.
Family patriarch Joe Jackson, 79, said at a news conference that the children were enjoying playing with other kids — something they do not normally do.
The documents state that although Rowe is the mother of the two older children, her whereabouts are unknown. The document simply listed "none" for the mother of the youngest child, Prince Michael II.
Supporting Katherine Jackson in her petition bid to administer the estate was Jackson's father, Joe Jackson.
say they have not heard from Rowe since their son's death. Rowe's attorney, Marta Almli, did not respond to an e-mail message seeking comment Monday. She previously said, "Ms. Rowe's only thoughts at this time have been regarding the devastating loss Michael's family has suffered."
Mark Lester, a former British child star who is godfather to Jackson's children, told The Associated Press he believes they belong with Jackson's mother.
"She is a very loving, kind and gracious woman, and she had a very close relationship with Michael and a very good rapport with her grandchildren," Lester said. "I know the kids are fine. They are deeply saddened by what's happened, but they're coping."
Meanwhile, authorities continued to investigate Jackson's death. Officials with the Los Angeles County coroner's office returned to the mansion he was renting at the time of his death and left with two large plastic bags of evidence.
Assistant Chief Coroner Ed Winter said the bags contained medication. He declined to elaborate.
Lawyers for Jackson's cardiologist Dr. Conrad Murray said the physician never prescribed the powerful drugs Demerol or Oxycontin for Jackson and did all he could to revive him when he found the entertainer near death.
Attorney Matt Alford told the AP it took as long as 30 minutes for paramedics to be called after Murray found Jackson with a faint pulse and performed CPR.
The delay was partly because Jackson's room in the rented mansion didn't have a telephone and Murray didn't know Jackson's street address to give to emergency crews, Alford said.
Eventually, Murray found a chef in the house and had him summon a security guard, who called for help while the doctor continued to perform CPR.
Jackson's father told reporters at the family compound that his son's funeral was still in the planning stages.
"It will be some private, but not closed all the way down to the public," he said without elaborating.
He added that his son would not be buried at, the sprawling playground he built in the rolling hills of Santa Barbara County then abandoned after going into seclusion following his acquittal on child molestation charges in 2005.
Jackson's father also used the news conference to plug a record company he said he's founding with a business partner.
"We have a lot of good artists pitching to come out," he said.
His son, who had not released a new recording or performed publicly in years, was believed to be hundreds of millions of dollars in debt at the time of his death. However, his finances are complicated and could take years to unravel.
Clearly one of his most valuable assets is his recording catalog, which his father could potentially rerelease through his new record company if the family gains control of his assets. There could also be recordings in Jackson's estate that he had never released.
The AP learned that Jackson had finished an elaborate video production project just two weeks before he died. The five-week project dubbed "Dome Project" could be the final finished video piece overseen by the star.
There's also a financial bonanza to be had in the Sony/ATV Music Publishing catalog of which Jackson owned 50 percent. The 750,000-song catalog includes music by the Beatles, Bob Dylan, Neil Diamond, Lady Gaga and the Jonas Brothers, and is estimated to be worth as much as $2 billion.
"Quite frankly, he may be worth more dead than alive," Jerry Reisman, general counsel for the Hit Factory, a recording studio where Jackson produced his best-selling album "Thriller," said recently.
Jackson nearly lost his beloved Neverland, which was once filled with amusement park rides and wild animals, to foreclosure in March. Billionaire real estate investor Thomas Barrack bailed him out at the 11th hour, setting up a joint venture with Jackson that took ownership of the 2,500-acre property.
The ranch's future is uncertain, but three of Jackson's brothers visited the estate with Barrack over the weekend. A spokesman for the holding company that now operates it said it was premature to talk about the ranch's future.