Michael Jackson's will, which has been called invalid by a number of the deceased pop singer's siblings, is once again under attack -- this time from a business partner of the singer's mother, Katherine Jackson.
In legal papers filed in U.S. District Court in Central California on Monday, Howard Mann -- who says he collaborated with the elder Jackson on a tribute book, "Never Can Say Goodbye: The Katherine Jackson Story" -- says that he is "in possession of evidence that casts substantial doubt on the validity of [Jackson's] will," which he will presumably present in court.
Mann is locked in a copyright battle with attorney John Branca and music executive John McClain, the executors of Jackson's estate. Mann hopes to prove that McClain and Branca have no legitimate claim to the material in question due to the alleged illegitimacy of the will.
In the papers -- which come in the form of a memorandum of opposition to a filing made by Branca and McClain -- Mann further says the pair have "defamed" him by "claiming that he is a profiteer, a thief and a man operating with utter contempt to the laws of intellectual property and the legacy of Michael Jackson."
Mann goes on to say that McClain and Branca have sought to sabotage the book, which was published in 2010, the year after "Thriller" singer Jackson's death at the age of 50.
"The Estate wrote threatening letters to 'The Oprah Winfrey Show' and 'Good Morning America prior to Katherine Jackson's appearance on these programs."
In June, a number of Michael Jackson's relatives -- including brother Randy and sisters Janet and Rebbie -- called for McClain and Branca to be replaced as the estate's executors and said that Jackson's will was "fake, flawed and fraudulent."
In a statement from Janet's lawyer earlier this month, the trio reasserted their claim, adding that they have nothing to gain financially from questioning the validity of the will.
"Michael's children will be the beneficiaries of Michael's estate," the statement reads. "What will be gained by a finding of invalidity is that the executors will be replaced and the estate and the guardianship will be managed in the best interests of the children, which is what Michael wanted."
Pamela Chelin contributed to this report.