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.