Romanian prosecutors are carrying out searches of mobile phones and laptops owned by influencer Andrew Tate, who has been detained on charges of being part of an organised crime group, human trafficking and rape.
The brothers have been remanded in custody since.
They appeared in handcuffs on Wednesday as they were escorted from a police van to the offices of Romania’s Directorate for Investigating Organised Crime and Terrorism (DIICOT), in Bucharest.
Ramona Bolla, a DIICOT spokeswoman, said the directorate was carrying out forensic searches of digital devices on Wednesday.
Responding to a journalist’s question as he arrived at the DIICOT offices, Andrew Tate was heard saying that “the case file is completely empty” and that “there is no justice in Romania”.
His brother was heard saying: "For my money, that is why I am in jail, I have money that they were going to steal.”
The Tates will remain in detention until late next month after a judge on Friday granted prosecutors a request to extend their detention by 30 days. It is not clear whether they have appealed the ruling.
Tate rose to notoriety in 2016 when he was removed from reality TV show Big Brother over a video that appeared to show him hitting a woman with a belt.
The former kickboxer has said women are partly responsible for being raped and that they belong to men. He is a self-professed misogynist.
On a podcast last year, he said he started making money when he lived in London by convincing girlfriends to videochat and share the profits.
"How can I use these women to make me money?" he said.
After the Tates and the two women were arrested, DIICOT said it had identified six victims in a human-trafficking case who had been subjected to “acts of physical violence and mental coercion” and were sexually exploited by members of the alleged crime group.
The agency said victims were lured in but later intimidated, kept under surveillance and subjected to control tactics while being coerced into engaging in pornographic acts for substantial financial gains.
A post appeared late on Tuesday on Andrew Tate’s Twitter account that read: “My case is a political operation designed to degrade my influence. Throughout history, unjust imprisonment has been used to silence empowering people. The game hasn’t changed.”
He also claimed he was sharing a cell with “cockroaches, lice and bed bugs”, which was part of a poem he wrote for his subscribers.
He wrote: "They are trying to break me.
"Thrown inside a cell without light.
"Cockroaches, lice, and bed bugs are my only friends at night.
"When the guards bring me to and from the courtroom, I stay absolutely respectful.
"They try to pour hatred into my heart."
Romanian authorities descended on a compound near Bucharest earlier this month and towed away a fleet of luxury cars that included a blue Rolls-Royce, a Ferrari and a Porsche.
They reported seizing assets worth an estimated $3.9 million. Tate unsuccessfully appealed the seizures.
Prosecutors have said that if they can prove the owners gained money through illicit activities such as human trafficking, the assets would be used to cover the expenses of the investigation and to compensate victims.