Image copyrightGETTY IMAGESImage captionMr Ko has denied he had an affair with presidential confidante Choi Soon-sil
The political scandal engulfing South Korea has culminated in Park Geun-hye's impeachment but according to one account, it all started with an argument over a puppy. The BBC's Tessa Wong unravels an outlandish series of events.
With his good looks and athletic build worthy of any South Korean pop star, Ko Young-tae has been the object of public fascination for months.
The former national fencer is closely linked to Choi Soon-sil, 60, the presidential confidante who now faces corruption charges.
Rumours about Mr Ko, 40, have saturated local media, which even labelled him Ms Choi's "toy boy".
But this week in front of a parliamentary committee he denied they were a couple.
Then, he proceeded to tell the extraordinary tale of how an argument prompted him to go to the press with revelations that would ultimately lead to the president's impeachment.
Read more: What is South Korea's presidential scandal?
Read more: The friendship behind the presidential crisis
Dressing the president
According to Mr Ko it all began in 2012, shortly after Ms Park was elected president.
Mr Ko, an Asian Games gold medallist, had long retired from fencing. His day job at that time was running a handbag and clothing company called Villomillo.
One day a friend asked him to show some of Villomillo's latest products to a mysterious buyer.Image copyrightGETTY IMAGESImage captionMr Ko has been the object of public fascination since the scandal blew up
"My friend asked me to bring some new items (to a designated place), so I did. That's when I saw Choi for the first time," Mr Ko recounted at a public hearing this week.
Ms Choi liked what she saw, and he began supplying her with items which would end up in Ms Park's wardrobe.
He gave around 40 luxury handbags made of ostrich skin and crocodile leather, and 100 bespoke pieces of clothing to the president.
They cost tens of thousands of dollars, and Ms Choi paid for all of them out of her own pocket, according to Mr Ko.Image copyrightAFP/GETTY IMAGESImage captionMs Choi is accused of influence-peddling
He strongly denied that he and Ms Choi became a couple - they were just friends, he said.
But he did not deny that she trusted him enough to give him appointments in two Germany-based companies which she owned.
As Ms Park's unofficial clothier Mr Ko also began to enjoy fame and success, especially after Ms Park was spotted toting a Villomillo bag in 2013, according to local media reports.
The brand drew celebrity customers and Mr Ko became a member of the local entertainment scene, even joining a celebrity baseball team called Play Boys.
In perhaps some of the most extraordinary testimony heard in South Korea's parliamentary chamber, Mr Ko described how trouble was brewing between him and Ms Choi.
In 2014, the businesswoman asked him to take care of her daughter's puppy. Mr Ko brought the dog to his house, then left it there as he went out to play a round of golf.
When he returned, he found Ms Choi in his home, furious with him for abandoning the puppy. The two had a "huge fight", he said.
From then on their relationship went downhill. "She treated me like a slave, swearing at me many times," he said in his candid account.
Angry and hurt, Mr Ko decided to exact revenge by going to the press about Ms Choi and Ms Park's relationship.Image copyrightAPImage captionThe scandal is centred on the close relationship between Ms Park and Ms Choi
Over the months he collected evidence of Ms Choi's power over Ms Park's administration, including CCTV footage of Ms Choi treating presidential aides as her personal servants. He eventually turned them over to a local broadcaster.
Then, in October, he did a TV interview where he alleged Ms Choi's "favourite thing" was to edit Ms Park's presidential speeches.
Reporters went digging for evidence to back it up, and obtained a tablet containing selfies of Ms Choi and files of presidential speeches.
The discovery, along with other revelations of Ms Choi's allegedly suspicious business dealings, sparked public outrage and launched a wide-reaching corruption inquiry that has ensnared even corporate bigwigs and celebrities.
Ms Park later admitted she gave Ms Choi inappropriate government access - including to her speeches - and apologised. But she has denied the allegations of corruption that prosecutors have laid down.Image copyrightGETTY IMAGESImage captionParliamentarians have voted to impeach Ms Park
The president has now been impeached, while in another twist Mr Ko is seen as a public hero, hailed by netizens for his "whistleblowing".
One lawmaker during the public hearing even praised him for "opening Pandora's box".
Asked in parliament if he feared opposing Ms Choi, the woman who had the president's ear, Mr Ko said "No".
"I was hot-tempered and never thought about that part," he declared. "I have no regrets."