getty; Alex Berliner/Shutterstock Britney Spears, Jamie Spears
In court documents filed in Los Angeles on Friday and obtained by PEOPLE, Britney, 40, responded to Jamie's December filing demanding that her estate make payments to his legal team for "ongoing fiduciary duties relating to the winding up of the Conservatorship of the Person and Estate," alleging that his financial misconduct during his tenure as her conservator put him in violation of California's standards of conduct.
Britney's lawyer, Mathew Rosengart, claimed in the filing that at the time the star's conservatorship was established in 2008, Jamie had owed Tri Star Sports and Entertainment Group, a business management firm run by Lou M. Taylor, at least $40,000.
While still indebted to the company, Jamie, 69, hired Tri Star to be Britney's manager, a role that Rosengart said awarded the firm "multi-million dollar commissions and fees" from Britney's earnings during the conservatorship.
In regards to Jamie's actions, Rosengart reiterated a question asked by Anthony Palmieri, the incoming president of the National Guardianship Association, in a December New York Times piece: "Is the conservator making decisions in the best interest of the conservatee or the business manager who they owe a debt to?"
"Although Mr. Spears contended that his daughter needed the Conservatorship because she was incapable of caring for herself or her affairs, Mr. Spears was intent on ensuring that she continued to generate significant earnings, a sizeable portion of which he distributed to himself and those within his inner circle," Rosengart later added.
Lawyers for Jamie and Taylor did not immediately respond to requests for comment.
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Friday's filing also included a declaration by Sherine Ebadi, an investigator at Kroll and former F.B.I. agent retained by Britney's legal team to investigate Jamie's management of the estate.
In it, Ebadi corroborated the claims made by former Black Box Security employee Alex Vlasov in The New York Times documentary Controlling Britney Spears that Jamie had the firm monitor Britney's phone, including private communications with her lawyer, and secretly record her in her bedroom during conversations with her now-fiancé Sam Asghari and her children (she shares sons Sean Preston, 16, and Jayden Jamed, 15, with ex-husband Kevin Federline).
Additionally, Ebadi alleged that Jamie would ask Black Box to send him "specific items from Ms. Spears's iCloud, such as therapy notes or text message," despite being "aware that he was expressly prohibited" from doing so without Britney's permission.
Along with surveilling Britney, Ebadi said that Vlasov claimed that the company had obtained private phone records from Britney's mother, Lynne, and others, including Britney's masseuse, to determine if they were speaking to the media.
According to Ebadi, Vlasov also said that Black Box would obtain GPS "ping data" to obtain the locations of certain people, including "former romantic interests" of Britney's, for surveillance.
The filing came just ahead of Britney's court hearing on Wednesday, during which Jamie's request for legal fees is expected to be discussed.
Britney's conservatorship was terminated on Nov. 12, five months after the singer made clear during a court hearing that she wanted it to end.
Rosengart, who has represented Britney since July, first filed court documents to move forward in asking L.A. Judge Brenda Penny to end Britney's conservatorship in September, weeks after Jamie, who was then her estate conservator, did the same.
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After Jamie — who had stepped down as Britney's personal conservator in 2019 — was officially suspended from his role as estate conservator on Sept. 29, Britney thanked Rosengart on Instagram, writing: "Thankfully I found an amazing attorney Mathew Rosengart who has helped change my life!!!!"
Weeks later, Rosengart filed additional court documents accusing Jamie of having ulterior motives after he unexpectedly reversed his stance in September on the necessity of Britney's conservatorship.
He filed a request on Oct. 1 to have Jamie deposed, and he questioned in court documents whether Jamie was "motivated by a desire to bolster his reputation or to avoid his deposition or responding to the outstanding discovery served on him in August."
For his part, Jamie has defended his role as the conservator of Britney's estate and has insisted that he only ever had his daughter's best interest at heart.
"Mr. Spears loves his daughter Britney unconditionally. For 13 years, he has tried to do what is in her best interests, whether as a conservator or her father," read a statement released by his former lawyer Vivian Thoreen in September.