Mathew Rosengart, Britney's attorney, entered a deposition for Sherine Ebadi in court on January 18, ahead of a hearing scheduled for January 19. In the documents, obtained by E! News, the former FBI special agent said she "corroborated" the claim that Jamie instructed Black Box Security "to plant a secret recording device in Ms. Spears' bedroom."

Ebadi (who was hired by Britney’s law firm, now an associate managing director in Kroll Associates' Intelligence and Forensic Investigations practice) said she reached her conclusion based on a briefing with Alex Vlasov, a former Black Box employee. Box Security first made the assertion when it spoke to The New York Times last year.

At the time, Jamie's attorney answered to detailed questions from the Times, saying, "All of her actions were within the parameters of the authority vested in her by the court. Her actions were done with the knowledge and consent of Britney, her attorney." appointed by the court, and/or the court. Jamie's registration as guardian, and the court's approval of his actions, speak for themselves."

In the latest filing, Ebadi explained that he personally questioned Vlasov at the Hotel Bel-Air in Los Angeles, "following the publication of these troubling allegations" and "at the direction of Ms. Spears' attorney."

"I corroborated the Times report on Mr. Spears' extensive surveillance efforts, including communications between Ms. Spears' attorney and client and private conversations in her bedroom," he claimed, he also wrote that Vlasov was " highly credible."

When Vlasov started working at the company in 2012, Black Box was already monitoring Britney's phone, according to the investigator, who stated she "personally reviewed" communications from Vlasov's personal devices that allegedly showed Black Box monitoring.

Based on conversations with Vlasov, Ebadi reportedly discovered that "Black Box was initially responsible for suggesting that a secret listening device should be placed in Ms. Spears's bedroom, but Mr. Spears 'loved' the idea and approved and instructed." to go ahead with the installation.

She said the Black Box employee who placed the secret device in the pop star's room "did so by taping it behind the furniture so it couldn't be seen, and added a separate battery to the recording device to allow continuous recording for a longer period of time".

"Communications between Ms. Spears and her court-appointed personal attorney, Sam Ingham, were among the private communications that Black Box and Mr. Spears monitored," the investigator wrote. "Mr. Vlasov told me that Mr. Spears was particularly interested in communications between the attorney and his daughter and wanted regular updates from Black Box on the content of those privileged messages. Monitoring of Ms. Spears' conversations with her attorney continued until at least 2020, when the owner of Black Box, Edan Yemini ] ordered Mr. Vlasov to stop reviewing privileged attorney-client communications."