A low-profile American heiress living in Italy has come under fire for donating $650,000 to three organizations that helped stage and promote the political rally on 6 January that was followed by the insurrection at the US Capitol by extremist supporters of Donald Trump.

Julie Fancelli, 72, who is the daughter of the founder of the Florida-based Publix supermarket chain, is facing criticism after new investigations revealed that she is the largest publicly known donor of the 6 January rally, the Washington Post reported.

At the rally held near the White House, Donald Trump urged supporters to go to the Capitol in an attempt to stop the 2020 presidential election victory by his Democratic rival Joe Biden from being officially certified by Congress.

Rioters then broke into the Capitol, although after hours of chaos and danger during which lawmakers and staff hid in fear of their lives, the election result was certified in the early hours the following day.

Worried relatives and those close to Fancelli say that her support of far-right groups could be prompted by Fancelli’s interest in conspiracy theorist Alex Jones.

On 29 December, eight days before the rally, Fancelli wired $300,000 to Women for America First, a non-profit that helped organize the 6 January rally, and $150,000 to the Republican Attorneys General Association’s non-profit arm, which covered robocalls promoting the march to “call on Congress to stop the steal”, reported the Washington Post last December, referring to Trump’s campaign to overturn the election result.

Fancelli also gave $200,000 to State Tea Party Express, a rightwing group, according to Sal Russo, a top consultant for the group. Russo told the Post that records of Fancelli’s donation have been provided to the House committee investigating the insurrection and that the money was used to pay for ads on the radio and social media, encouraging supporters of Donald Trump to participate in the rally. Russo said to the Post that he does not support the violence that happened at the Capitol.

Information on how expenses such as travel and hotel stays were covered for the thousands of Trump supporters who attended the rally and march on the Capitol is still being investigated, but details, including Fancelli’s substantial , financial support, continue to emerge.

Democratic representative Bennie Thompson of Mississippi, the chair of the House committee investigating the events that led to the 6 January insurrection, told the Post that he believes Fancelli “played a strong role” in financially backing the rally. “We’re trying to follow the money,” said Thompson.

While Fancelli has not responded to requests for comment from the Post since August, she has addressed her involvement in the 6 January rally.

“I am a proud conservative and have real concerns associated with election integrity, yet I would never support any violence, particularly the tragic and horrific events that unfolded on January 6,” said Fancelli via a statement released 10 months ago.

Previously, after an initial report about the $300,000 Fancelli donated before the rally, Publix Super Markets released a statement via social media, saying that Publix would not comment on Fancelli’s actions as she was not an employee of Publix or involved in the business. Following an inquiry from the Post last week about Fancelli’s total contributions, Publix said that the company “cannot control the actions of individual stockholders” and issued a rebuke of her actions.

“We are deeply troubled by Ms Fancelli’s involvement in the events that led to the tragic attack on the Capitol on January 6,” said Publix in a statement to the Post.

Fancelli had planned to attend the rally herself, even booking a room at the upscale Willard hotel, but decided not to travel due to the pandemic, according to a Republican who was familiar with her donation, the Post reported.