Britney Spears officially requests for father to be removed from conservatorship

Britney Spears's new lawyer, Mathew Rosengart, promised to move aggressively to oust Jamie Spears if the singer's father didn't step down from the conservatorship voluntarily — and that's exactly what the former federal prosecutor did on Monday.

Rosengart petitioned to have the elder Spears removed as conservator of her estate, asking the court to instead appoint CPA, Jason Rubin. According to Rubin's website, he has "managed complex trust portfolios containing real estate and other financial assets valued over $35 million." Britney's estate was previously estimated to be around $60 million. Rubin has also worked "on financial elder abuse litigation." The "Toxic" singer has accused her father of conservatorship abuse, saying he and others who have profited off the legal guardianship should be in jail.

The filings come as Judge Brenda Penny approved Bessemer Trust's request to withdraw as co-conservator of Britney's finances, leaving only her father in charge.

Some supporters of the #FreeBritney movement are wondering why the singer's attorney didn't petition to end the conservatorship altogether, but the legal nuances are more complicated.

"Although Britney's attorney will likely file a petition to terminate the conservatorship soon, that process will take time for the court to decide because the court has not acted on its own to end the conservatorship. Meanwhile, Britney's attorney wants Jamie to be replaced immediately to avoid further damage," attorney Cristopher Melcher, of Walzer Melcher, tells Yahoo Entertainment.

"With Bessemer Trust allowed to resign, it leaves Jamie Spears as the sole conservator over the estate, meaning he has complete control over Britney's finances. Jamie is not a professional fiduciary and has no qualifications to manage an estate like Britney's," he adds.

Monday's petition calls Rubin "an objectively intelligent preference," with Rosengart arguing that since the court ruled Britney has "sufficient capacity to choose her own legal counsel," she also has sufficient capacity to make this nomination.

"Britney's court-appointed counsel asked a year ago for Bessemer to be appointed, which Jamie opposed. The legal fees Jamie incurred in unsuccessfully resisting Britney's request were charged to her estate. Britney's money is being used to pay the fees for her father to be a conservator, against her wishes, and the fees for Jamie's attorney to oppose her wishes. It is an abuse of Jamie's fiduciary duty to act adversely to Britney," Melcher adds.

Rosengart claims in documents on Monday that Jamie is "guilty of misfeasance or malfeasance warranting the imposition of surcharges, damages, or other legal action against him."

"Jamie should do the right thing by resigning immediately. He is not speaking with Britney, and she has accused him of abuse. Her sons were granted a restraining order against Jamie to protect them. That alone should have been a red flag for the court," Melcher continues. "There is no legitimate reason for Jamie to remain in control over her finances. There is a conflict of interest between Jamie and Britney because she is making accusations against him, and he is trying to deflect blame to others. The court should have removed him. It is maddening that the court has not acted and has allowed Jamie to remain in control."

A hearing has been set for Dec. 13 to discuss Jamie's removal and whether Rubin will be appointed.

Access Hollywood video courtesy of NBC/Access Hollywood.