The handlers of Michael Jackson's probate and guardianship cases have much to do at a hearing Monday meant to tackle a number of estate and family issues. At least one major hurdle was cleared last week with a custody agreement between Jackson's mother, Katherine Jackson, and Deborah Rowe, the biological mother of the singer's two oldest children. Los Angeles Superior Court Judge Mitchell Beckloff has deferred hearing arguments or making rulings on several motions brought by attorneys for Katherine Jackson and the two men who have temporary control of the pop icon's financial matters: attorney John Branca and music executive John McClain. Jackson's estate has been described in court documents as having an estimated value of more than $500 million, but its actual current worth is about $100 million, and could increase in value to $200 million or more with some financial restructuring, according to a person briefed on the matter. The person was not authorized to speak publicly and requested anonymity. Branca and McClain could leave Monday's hearing with a firmer rein on the estate. Similarly, Katherine Jackson could emerge with guardianship of her three grandchildren, since her agreement with Rowe, which grants the singer's ex-wife visitation rights, means no one is expected to challenge the current arrangement. Meanwhile, Katherine Jackson said in a recorded phone interview with Geraldo Rivera that she doesn't believe her son died of natural causes. The interview aired Sunday night on “Geraldo at Large” on the Fox News Channel. “All I know that my son is dead, and I don't think he just died of natural causes or whatever,” she said. “He's too young to have that. Something happened. I don't know what it was. And I can't say.” The to-do list for Monday's hearing has grown in recent weeks, with Beckloff deferring decisions on several issues, most of which have to do with Jackson's finances.