The 82-year-old left her Calabasas, California, home July 15, to fly to Albuquerque, New Mexico, to attend a Jackson brothers' concert two days later. Ribera believes Jackson could be with her eldest daughter Rebbie Jackson, with whom she left for Albuquerque.
However, when Paris, Michael Jackson's 14-year-old daughter, called Rebbie Jackson and another aunt, singer Janet Jackson, over the past several days, she was told each time she could not speak to her, Ribera said.
"The kids were trying to get a hold of their grandmother and they haven't been able to reach her for almost a week," Ribera said. "They are told she's unavailable."
"I'm concerned that she's not safe," Ribera was quoted as saying. Jackson is currently in the midst of a dispute between several of her children and her advisers over her finances and legal affairs.