The former president is not the first public official to be accused by witnesses of wrongdoing by witnesses at Guzmán's trial. Jesús Zambada García, Guzmán's former accountant, said he paid off former public security secretary Genaro García Luna, plying him twice with suitcases containing at least $3 million. García Luna called the accusations "lies, defamation and perjury."
A two-time escape artist with a base of social support in his native Sinaloa state, Guzmán, 61, rose from childhood impoverishment to leading the Sinaloa cartel, which transported tons of cocaine from Colombia to the United States, smuggling its illegal merchandise through tunnels under the border, and reportedly bribed public officials across the country.
His ability to evade the authorities and seemingly mock their attempts to capture him came to embody impunity in Mexico and the difficulties in the country's crackdown on drug cartels and organised crime, which has cost more than 200,000 lives and left more than 30,000 missing since 2006.
Guzmán was extradited on the eve of President Donald Trump's inauguration in January 2017 to face charges of trafficking cocaine, heroin and other drugs into the United States.
The accusations against Peña Nieto captured attention in Mexico, where the former president's approval rating cratered as he left office, according to polls, and his party is so unpopular that it has considered changing its name.
"This would merit an investigation in order to know if it's true. The @lopezobrador_ government should take it seriously. The problem is . . . we know they won't do anything," journalist and columnist Mario Campos tweeted in Spanish.
President Andrés Manuel López Obrador won election in a landslide, promising to clean up corruption. He stunned many in Mexico, however, by saying he preferred not to prosecute outgoing public officials accused of corruption.
López Obrador has a history of equating the actions of allegedly corrupt politicians to those of the "mafia." He did so as he toured the country over the past 12 years, visiting all of Mexico's more than 2,400 municipalities, including many overrun by organised crime.
On a 2016 tour of Sinaloa shortly after El Chapo's arrest, he told a crowd: "Nothing is said about the cartel that robs the most: the Los Pinos Cartel" - a reference to the presidential palace López Obrador refuses to live in - "which is headed by Enrique Peña Nieto."