The plot thickens for the man once called the "Brazilian Donald Trump" as former Brazilian President Jair Bolsonaro was detained on Saturday at his residence in Brazil's capital to prevent a possible "attempted escape" - police and court authorities have said.

He has been on house arrest, and the 70-year old politician is just days away from starting a stiff 27-year prison sentence - though appeals are expected - but he's now been taken to the headquarters of the federal police in Brasilia. What's being called a 'preventative arrest' warrant was reportedly requested by the police themselves and authorized by the Supreme Court, after which officers came to Bolsonaro's home to arrest him.

Supreme Court Justice Alexandre de Moraes has claimed that Bolsonaro's ankle monitor, which he has worn since mid-July, was tampered with or violated early Saturday morning.

"That information shows the intent of the convict to break the ankle monitoring to assure his escape is successful, which would be made easier by the confusion that would be caused by a demonstration organized by his son," the justice, who oversaw the case, said.

Further, "He said there was a chance of Bolsonaro fleeing to embassies in his neighborhood to request political asylum," according to the Associated Press. "The Supreme Court justice also mentioned other defendants in the coup case and political allies of the former president leaving Brazil to avoid jail."

Given the former Brazilian leader's chummy friendship with President Trump, who has frequently weighed in strongly on Bolsonaro's behalf and urged his release, his political opponents have feared he could seek the safety of the US once again.

Bolsonaro's lawyers starting Monday will present their case to appeal the arrest and dismiss the allegations he was trying to escape.

CNN has described that his political opponents have also feared that mass protests in support of Bolsonaro could be whipped up around his residence and used as a means of escape. Citing his son, the report says:

Flávio Bolsonaro described the vigil, initially planned for Saturday evening local time, as an opportunity to pray for his father following recent reports of ill health and “for the return of democracy in our country.”

“Are you going to fight for your country or just watch everything on your phone on your couch at home?” he asked his followers in a social media video.

Brazil’s Supreme Court said on Saturday that it had received information about the “summoning of supporters” to the vigil which indicated a “high possibility of an attempted escape.”

The gathering could “reach a large scale” and last for several says, resulting in “unpredictable effects, developments, and consequences,” the court said.

Bolsonaro has already been barred from running in future elections, and a lengthy appeals process which is still expected could push the proceedings closer to the 2026 presidential campaign - and all the while Bolsonaro has insisted he will be a candidate.

The Trump White House has chaffed at him being placed under house arrest, and has repeatedly publicly denounced the Lula government for a state 'witch hunt'.