Police in Argentina seized information tied to Maradona's treatment and medical history from his doctor, Leopoldo Luque, after questions over the former soccer player's death were raised.
Thousands of fans lined up from the early hours on Thursday to file past Maradona's wooden casket in the presidential palace. Argentina's beloved soccer star died on Wednesday.
The former president crossed the border from Argentina and was welcomed by a large group of supporters, just a day after his former economy minister, Luis Arce, was sworn in as president.
Once there were 100 cases, the government imposed broad confinement measures. More than seven weeks later, with 317 coronavirus-related deaths, Argentina is easing its lockdown outside Buenos Aires.
Local leaders in the South American nation are calling on the president to take far stronger measures to tackle the virus, after the number of identified cases rose from 170 to 922 in just a day.
The preliminary finding, reported by Argentine researchers on the Antarctic Peninsula, would be the continent's hottest temperature on record if verified by the World Meteorological Organization.
President-elect Alberto Fernández, backed by his running mate, former two-term president Cristina Fernández de Kirchner, won a convincing victory over conservative incumbent Mauricio Macri.