Why is a $25,000 campaign donation Donald Trump made in September 2013 to Pam Bondi, a Republican running for re-election as Florida’s attorney general, now such a big deal?

Trump circumvented Internal Revenue Service (IRS) rules by routing the money through a charitable entity, the Donald J Trump Foundation, which is prohibited by law from making political donations. More controversially, however, Bondi’s office was at the time mulling whether to join a New York state probe into allegations that customers who paid thousands of dollars to Trump University, Trump’s for-profit education company, for a real estate investment course were ripped off. Just days after Trump’s donation arrived, Bondi dropped her investigation into the alleged fraud, citing “insufficient grounds” to proceed.

The donation was three years ago. Why is the case back in the news now?

The story gained some traction in June when the Associated Press reported that Bondi had personally solicited the donation from Trump to a political group supporting her re-election campaign. But last week’s Washington Post report that Trump had paid the IRS a $2,500 penalty for the “improper” contribution sparked renewed scrutiny, quickly followed by a “he-said, she-said” disagreement this week over whether Trump and Bondi had ever actually discussed the affair.

So if Trump paid the IRS a penalty, does he admit he did wrong?

Not at all. The fact that Trump’s charity made the unlawful donation instead of Trump himself was “just an honest mistake” according to Jeffrey McConney, senior vice-president of the Trump Organization. So, apparently, was the fact that the Trump Foundation’s tax filing for that year did not record the donation to Bondi’s group, but did claim that a $25,000 gift was made to a charity in Kansas with a similar-sounding name, even though no such donation appears to have been made. In the words of the Washington Post, “the prohibited gift was, in effect, replaced with an innocent sounding but non-existent donation”.

That’s nonsense, insists McConney, who said Trump immediately reimbursed his foundation and filed corrected paperwork with the IRS as soon as the “errors” were brought to his attention in March by the Post and the watchdog group Citizens for Responsibility and Ethics in Washington.

And what of Bondi? Is she also contrite?

Despite flak from several Florida newspapers and the suggestion from the Miami Herald that she was “bought and paid for”, the state’s abrasive attorney general – who has publicly endorsed Trump for president – remains defiant. Having always insisted her office never formally investigated Trump University, and found no basis to do so, Bondi was forced on to the defensive on Tuesday after Hillary Clinton spoke to reporters about the controversy. “I will not be collateral damage in a presidential campaign, nor will I be a woman bullied by Hillary Clinton,” Bondi told Fox Business Network.

So has the scandal run its course?

Unlikely. Huffington Post disclosed late Tuesday that Trump subsequently allowed Bondi to use his sumptuous Mar-a-Lago estate in Palm Beach for a $3,000-a-head re-election fundraiser in March 2014, just months after she dropped the fraud probe. The new revelation raises further questions over whether Trump was thanking Bondi, and could weaken his own line of attack against Clinton over the sourcing of her own campaign donations.