Brazil’s former president, Jair Bolsonaro, has been ridiculed by his political opponents after he was questioned by federal police as part of a criminal investigation into January’s alleged coup attempt and claimed he had shared a video questioning last year’s election result “by mistake”.

Bolsonaro spent more than two hours in the company of police investigators on Wednesday morning, nearly four months after thousands of hardcore supporters ran riot in the capital, Brasília, in what the new administration called a botched coup intended to reinstall the far-right former army captain as president.

The pro-Bolsonaro riot failed and the winner of last year’s election, his leftist rival Luiz Inácio Lula da Silva, remains in power.

But federal investigators are now working to identify and punish the perpetrators of January’s violence as well as the financial backers and organizers of the turmoil.

Speaking earlier this week, Lula’s justice minister, Flávio Dino, said he believed “traitorous” army generals were involved in the conspiracy. “They go around calling themselves patriots but they are traitors,” Dino said.

Bolsonaro was forced to appear before police officials on Wednesday morning over a video he shared on Facebook two days after the 8 January uprising that claimed – without proof – that the election he lost had been rigged by electoral authorities.

Brazilian media reports claimed Bolsonaro told investigators he had republished the video by mistake and while under the effect of morphine he had received after being taken to hospital in the US.

Bolsonaro’s lawyer, Daniel Tesser, told reporters the former president “rejected any kind of anti-democratic deed” or behaviour which sought to destabilize the democratic order.

Opponents of the former president – who has a long and well-documented history of undermining Brazil’s democratic institutions and electronic voting system – scoffed at those claims.

“He has the ears, the snout and the tail of a coup-monger and he’s going to tell the federal police he’s not a coup-monger?!” tweeted the president of Lula’s Worker’s party (PT), Gleisi Hoffmann.

The federal police investigation is far from the only legal difficulty facing Bolsonaro, who is widely expected to be stripped of his political rights in the coming months by Brazil’s electoral court as a result of an investigation into online disinformation.

The former president, who no longer enjoys political immunity from prosecution, faces at least 16 separate investigations as well as a growing scandal over suspicions he tried to illegally take possession of millions of dollars worth of jewelry given to him by the government of Saudi Arabia.

Bolsonaro’s political backers are reportedly considering who might replace their leader if his legal woes mean he is unable to challenge Lula in the 2026 presidential election. One option is said to be his wife, the former first lady Michelle Bolsonaro.