If Mr Nawrocki is concerned about the impact of his deception on the election, he didn't show it when asked to comment on his apparent split personality: "Literary pseudonyms are nothing new in Polish academia" he said, before going on to praise himself again: "There was only one historian in Poland who had the courage to study organised crime, and I was that historian. But Tadeusz Batyr had no academic research or sources to refer to."
According to Polish Newsweek magazine, Nawrocki's "fascination" with the underworld is well-known. Local media have reported that the historian is acquainted with several figures associated with organised crime and biker gangs in Poland. Mr Nawrocki says any interactions are strictly professional.
Nawrocki is currently in second place in the presidential race behind Warsaw mayor Rafal Trzaskowski, who is from Prime Minister Donald Tusk's liberal Civic Coalition party. In third place - far-right candidate Slawomir Mentzen, who has recently seen a surge in popularity. His Confederation party advocates ultra-low taxes, stopping what it calls "Leftist ideology" and an end to immigration.
The results of this election could have reverberations far beyond Warsaw, too. Poland is a key partner in the West's support for Ukraine. Up to 95% of military aid sent to the country passes through Poland, and around 10,000 US troops are stationed here. Poland shares borders with both Ukraine and Russia and is rapidly expanding its armed forces, vowing to spend almost 5% of GDP on the military this year – the highest in NATO.
PiS-backed Karol Nawrocki has blamed "the decisions of the European elites" for starting the war in Ukraine. Senior figures in the PiS party, which campaigns for lower taxes and energy security, have accused the EU of plotting to interfere in the election.
"This election is hugely important," says political analyst Marcin Zaborowski, "\[Tusk ally\] Trzaskowski is the only candidate that is pro-European, an Atlanticist and supportive of Ukraine. He represents continuation in foreign policy."
And this election matters for Poles at home, too. Better abortion access, same-sex marriage and rule of law reform were all promised by Donald Tusk when his coalition came to power in 2023. But President Andrzej Duda, aligned with PiS, has the power of veto over legislation. That's why, so far, Mr Tusk has been unable to pass any significant reforms.
"The people who voted for \[Tusk\], especially first-time voters or women, may be very disappointed," says Mr Zaborowski, "But if Civic Coalition gets a president that supports their programme, that will be a real boost to what this government can do."
With less than two months before the first round of voting, Civic Coalition's Trzaskowski is in the lead. But with the polls narrowing, Karol Nawrocki has been out campaigning energetically – eager to persuade voters that he, and not the shadowy Tadeusz Batyr, is their choice for President.