US President Donald Trump has accused a federal prosecutor he appointed of folding "like an umbrella" after she moved to drop charges against a three-time Olympian accused of vandalising the Lincoln Memorial Reflecting Pool.He told reporters in the Oval Office on Monday that Jeanine Pirro, the US attorney for the District of Columbia, "made a mistake" and "choked" by abandoning the case.It comes as rumours circulate that Mr Trump is weighing an attempt to oust her from the role she has held for little more than a year.Here's what to know about the emerging feud.First, catch me upThis spat relates to the months-long drama over Mr Trump's plagued Lincoln Memorial Reflecting Pool renovation.Back in April, the president ordered a multi-million-dollar renovation of the monument, which aimed to fix leaks and turn the pool a colour he called "American flag blue".No-bid contracts were awarded to two businesses Mr Trump had personal ties to, bypassing a legal requirement to seek competing bids by citing urgency to get the job done in time for Independence Day celebrations.Ducks swimming in the Reflecting Pool after an algal bloom turned the water green. (Reuters: Ken Cedeno)Just days after the pool was refilled on June 4, an algae bloom turned the waters bright green.Park workers were at one stage seen emptying jugs of hydrogen peroxide into the water in an attempt to clear the algae.By June 9, the newly installed blue lining at the bottom of the pool had begun to peel.Without providing evidence, Mr Trump later alleged vandals had poured "corrosive and destructive chemicals" into the pool.A National Park Service worker dumping bleach into the water on June 16. (Reuters: Jonathan Ernst)On June 19, David "Davey" Hearn, who canoed for the United States at the 1992, 96 and 2000 Summer Olympics, stopped by the pool during a 102-kilometre bike ride and reached into the water to examine the peeling coating.Mr Hearn, who owned a company that made composite materials for watercraft, told the Associated Press he briefly touched a chunk that was still attached to the side of the pool, then let go when a park worker told him to.National Guard troops and Park Police then detained him for five hours, and he was later indicted for "maliciously" damaging the lining.In July, Mr Hearn pleaded not guilty to one felony count of property destruction, and a trial was scheduled to begin on September 28 in the DC Superior Court.What happened with Hearn's case?Prosecutors ultimately decided to drop the case.In court papers filed by Ms Pirro's office on Friday, the prosecution said it had received new information that undermined the charges laid against Mr Hearn.The filing cited documents provided by the Department of the Interior, which showed the damage to the pool's sealant was the result of a "botched installation" by a contractor and the "rush to complete the project".A recent visual inspection also revealed damage throughout the pool, including in the middle, where prosecutors say a vandal would not likely have attempted to peel the lining."Given all of this newly discovered information, it is difficult to attribute the widespread damage to the Reflecting Pool to vandalism, let alone to establish that fact beyond a reasonable doubt," the filing, which asked a judge to formally dismiss the case, said.The move to dismiss the charges against Mr Hearn was an embarrassing setback for the Department of Justice and marked a rare moment during Mr Trump's second term of an aide or political appointee openly defying him.And Trump wasn't happy?He was not.The president took to Truth Social on Saturday to voice his displeasure over the move, saying he "100%" disagreed with Ms Pirro."I don't know what she was thinking? To me, it was a pure case of VANDALISM, that included the grass, which had a big 86 47 emblazoned in giant letters on it, and other elements of the surrounding area," he wrote, linking the damage to an incident where numbers were found emblazoned onto a nearby lawn."There may have been some contractor difficulty, but the major damage was caused by VANDALS!"He later shared webcam video of the Reflecting Pool that showed some passers-by dipping their hands into the water, accusing them of cutting the sealant with "a knife or box cutter, for all to see".Mr Hearn was never accused of cutting the sealant, but of "forcefully and violently" pulling the liner "with both hands".Jeanine Pirro had previously accused David Hearn of "maliciously" pulling at the sealant. (Reuters: Cheney Orr)Mr Trump was still fuming two days later, discussing the matter with reporters in the Oval Office for several minutes on Monday."Frankly, I think [Ms Pirro] choked because the judge was really vicious," he said."Instead of going after the people that did it, the judge went after her and went after her department, and I guess she choked. I don't know what the hell happened."I was disappointed with Jeanine Pirro, really disappointed."What about the rumours?Two unnamed sources familiar with the president's thinking told CNN it was "highly likely" Ms Pirro would be removed from her job, with one adding that Mr Trump felt "blindsided" by her filing.Mr Trump was asked whether he was reconsidering Ms Pirro's role while speaking with reporters on Monday but didn't answer directly."I don't know what", he said, before sledging the journalist who had asked about the rumour."You're fake news. Don't ever talk again."The Lincoln Memorial Reflecting Pool was drained again on July 10. (AP: Mark Schiefelbein)On Monday evening, Ms Pirro was seen walking into the White House. Also spotted was Department of the Interior secretary Doug Burgum, who has been outspoken in defending the president's suggestions that vandalism was to blame.Sources told CNN Ms Pirro was not fired during the meeting, nor did she resign.ABC/AP