SEOUL • Special prosecutor Park Young Soo is going after South Korea's most powerful business leaders and politicians, but he has faced tougher opponents before.
In 2015, Mr Park was slashed in the neck with a box cutter by a man he defeated years earlier during a stint with a private law firm.
Now, Mr Park has indicted 30 people in an investigation into corruption surrounding President Park Geun Hye, after a 70-day probe.
Most prominent is billionaire Lee Jae Yong, the de facto head of the Samsung Group, who is fighting allegations that the conglomerate, known as a "chaebol" in South Korea, traded cash for political favours.
Putting the heir to a US$238 billion (S$337 billion) empire behind bars, even temporarily, is the biggest accomplishment yet for Mr Park, whose career includes arresting two other chaebol bosses.
Business leaders have cycled in and out of jail for years, but tolerance among South Koreans seems lower this time, with people marching in downtown Seoul and leaving baskets of flowers and chocolates outside Mr Park's office with messages such as "Keep on fighting!"
The 65-year-old former head of the Seoul High Prosecutors' Office was appointed by President Park last November, amid allegations of influence peddling that extended to her long-time confidante Choi Soon Sil. Both have denied wrongdoing.
Mr Park said last December: "The public's desire is for the special counsel team to uncover the whole truth, and I intend to do just that and devote my everything to it."
Mr Park, who is not related to the President, had a history with chaebols even before this latest investigation. In 2003, he uncovered accounting fraud at SK Group and arrested chairman Chey Tae Won. In 2006, he oversaw the probe into Hyundai Motor's slush funds, which led to the arrest of chairman Chung Mong Koo.
Chey and Chung were both convicted and subsequently pardoned.
For all that, local media started calling Mr Park the "Chaebol Grim Reaper". He earned his master's degree in law at Korea University and started his career in 1983 in the Seoul city prosecutor's office.
Early days involved busting gangsters, gamblers and drug traffickers. He was promoted to chief of the Seoul High Prosecutors' Office before retiring in 2009.
When he was appointed special prosecutor, Mr Park said he knew the magnitude of what he was about to undertake. But he said in a radio interview: "When there was a request to investigate wrongdoings, I could not refuse. That would go against the principles I have lived by."