Brazil’s Supreme Court has agreed to include right-wing former president Jair Bolsonaro in its investigation into the storming of government buildings in Brasília.
It is the first time that Mr Bolsonaro has been named among those potentially responsible for the 8 January riots.
It comes days after Mr Bolsonaro posted a video questioning the legitimacy of October’s presidential election.
Prosecutors said Mr Bolsonaro may have incited a crime by making such claims.
They asked the Supreme Court on Friday to include the ex-president in the investigation.
The Bolsonaro video claimed that President Luiz Inácio Lula da Silva was not voted into office but rather chosen by the Supreme Court and Brazil’s electoral authority.
By questioning the vote “Bolsonaro would have publicly incited the commission of a crime”, the office of the prosecutor general (PGR) said in a statement.
While the video was posted after Sunday’s riot and later deleted, the prosecutor general’s office argued its content was sufficient to justify investigating Mr Bolsonaro’s conduct beforehand.
Supreme Court Judge Alexandre de Moraes announced Mr Bolsonaro would be included in the probe into what the PGR said was the “instigation and intellectual authorship” of the rioting.
“Public figures who continue to cowardly conspire against democracy trying to establish a state of exception will be held accountable,” said Justice de Moraes.
Thousands of radical Bolsonaro supporters, who continue to claim that the election was rigged, stormed the country’s Supreme Court, Congress and presidential palace on Sunday.
They had been camping in and around the capital Brasilia for weeks calling for a military coup.
Meanwhile, Mr Bolsonaro has been admitted to a hospital in Florida with abdominal pain, his wife said.
He left Brazil for the United States in late December, after refusing to take part in the handover of power to Lula.
Many businessmen and officials are being investigated, including Brasilia’s former head of security, Anderson Torres, who flew to the US ahead of the riots.
On Thursday, police visited his home and found a document reportedly trying to reverse the election result.
Mr Torres argues the document has been taken out of context, but Justice Minister Flavio Dino has said he must turn himself in by Monday or face extradition.
Earlier, Lula accused Mr Bolsonaro’s allies of aiding an attack on the presidential palace on Sunday.
More than 1,200 people have been formally arrested and are being charged in relation to the riot at Brazil’s Congress.
Arrest warrants have already been issued for several top officials accused of being “responsible for acts and omissions” that led to the riots.