By Jen Heger - Breaking Celebrity News Assistant Managing Editor

UPDATE: Detectives with the LAPD  Monday said they have had contact with Katherine Jackson and she is on a planned vacation in Arizona.

Michael Jackson's ex-wife, Debbie Rowe, the mother of his children Prince and Paris, is extremely concerned for Katherine Jackson, and she’s vigorously monitoring the situation, Breaking Celebrity News is exclusively reporting.

"Debbie is actively monitoring the situation and is extremely concerned for Katherine. She has tremendous respect and love for Katherine and is also concerned for the children and is angry that Paris has been unable to talk to Katherine for the past week," a source close to the situation tells Breaking Celebrity News.

As we previously reported, Katherine Jackson, 82, was reported missing to the Los Angeles County Sheriff's Department after her grandchildren, Paris, Prince, and Blanket were unable to reach her all week.

"While Debbie hasn't been a strong presence in the children's lives, she loves them tremendously and is concerned for their well being," the insider says. "Debbie and Katherine were able to reach an out of court custody agreement in the months after Michael died. Debbie had no interest in fighting Katherine for custody of the children. However, if Katherine has suffered a health setback, this could very easily end up back in court because Debbie has very strong feelings about Michael's siblings having any role in caring for the children."

Meanwhile, Randy, Jermaine, Tito, Rebie and Janet Jackson all are demanding that the late singer's Estate executors John Branca and John McClain resign. They wrote a letter