First, Life is arrested. He isn't simply summoned Changwon Prosecutor's Office to be investigated or to be a witness. I've seen so many fake Koreans here claiming that arrest and investigated uses the same word. No, if Life was simply summoned there to be investigated, the article would use the word '소환' not '체포'.
Second, Life is arrested by Prosecutor's Office. The Korean Prosecutor's Office is superior investigation branch to Korean police. There are multiple scandals in Korean sports scene that are being investigated by Korean police and Prosecutor's Office; however, very few of them have been arrested by Prosecutor's Office. One of other sport's match fixing main suspect had been arrested by police; however, he recently was released by Prosecutor's Office for lack of evidence. The fact that Life was arrested by Prosecutor's Office makes this case worse since it means they have enough evidence to suspect Life as a match fixer.
Third, Life is arrested with a proper warrant issued by Korean Judicial Branch. Every time Prosecutor's Office properly arrests someone, they have to receive warrant from Judicial branch. This means Prosecutor's Office applied for a warrant to arrest Life and submitted evidences to Judicial Branch, and Judicial Branch found the evidences sufficient enough issue warrant to arrest Life. This makes the matter even worse.
Conclusion or TL;DR, Life is currently arrested with evidences which multiple Korean government branch found sufficient to suspect him of guilt. YES, Life's guilt is not proven, but is the matter simple as some detective making wrong guess? NO, this is why Korean communities are VERY worried, and some of redditors should get get off their high horse and take matter seriously.