Seoul, South Korea (CNN) -- South Korea's most wanted man, who is believed to have ties to the company that operated the ill-fated Sewol ferry, has eluded arrest for weeks, leaving authorities red-faced for not finding the high-profile billionaire.
The Sewol ferry sank on April 16, killing 288 people on board.
Through an investment vehicle and subsidiary, Yoo Byung Eun, 73, and his two sons are believed to have controlled the shipping company that operated the ferry, according to the semi-official Yonhap news agency. In late April, Yoo's representatives sent a statement denying that he had any direct or indirect connection to Chonghaejin Marine Company.
Yoo is wanted for questioning in connection with an investigation into alleged funds embezzlement, tax evasion and other irregularities that prosecutors say could have contributed to the sinking. A South Korean court has issued a warrant for Yoo's arrest. Investigators are looking into why the ferry capsized, including factors such as imbalance of weight on the ship, overloaded and improperly secured cargo, and actions by the company and crew.
The Incheon District prosecutor's office said on Tuesday: "The ones who are most directly responsible for the accident are officials with Cheonghaejin ... Our prosecutor's office is currently investigating Yoo Byung Eun, who is standing at the very top of it."
Yoo has defied summons to report to the prosecutor's office, and gone into hiding. The prosecutor's office has come under public criticism for waiting for Yoo to appear of his own volition, which some say gave him plenty of time to flee.
Searching for Yoo
Yoo is known as the "millionaire without a face" because of his reluctance to appear in public. Yoo has four sons and daughters, three of their whereabouts are unknown.
Four members of the religious group his father-in-law founded have been arrested, accused of aiding Yoo. South Korea's Justice Department said it requested its French counterparts to make the "provisional arrest" of his daughter. The younger Yoo has been detained by French authorities in connection with the Sewol investigation, said Magalie Josse, Paris court spokeswoman.
French authorities will determine whether to extradite the younger Yoo, according to the South Korea's Ministry of Justice.
South Korean President Park Geun-hye lashed out against the Yoo family this week.
"The Yoo Byung Eun family, who is the fundamental cause of this tragedy, is mocking the law and causing public rage instead of coming in front of the people to apologize and tell the truth," she said on Tuesday. "Such an act by Yoo's family is a challenge to our society and an act of crime that cannot be protected."
This week, the reward for information for the capture of Yoo was raised to nearly $500,000 and about $100,000 for his eldest son. South Korean media showed pictures of possible disguises for Yoo and his appearance throughout the years.
Yoo's religious group
Yoo is a religious figure of Gu Won Pa (which translates to "salvation group"), also known as the Evangelical Baptist Church.
Some members of the group have protested in front of the prosecutor's office in what they consider religious persecution. Last week, nearly a hundred members of the religious group stood outside its mountain compound as investigators arrived to search for Yoo. The supporters said the church had nothing to do with the allegations and likened the case to religious persecution, according to Yonhap
Investigators have also started looking into the practices of the group.
"We are also in cooperation with nationwide police forces closely investigating buildings and lands related to Gu Won Pa," said an official from the prosecutor's office. "We are also not ruling out that he (Yoo) was smuggled out of the country and hence, we are collecting intelligence concentrated on ports."
Yoo has had brushes with the law. He was convicted on fraud charges in the 1990s and spent four years in prison, according to South Korean media reports. In 1987, he was under investigation after more than 30 people from a religious group were found dead, bound and gagged in a factory outside of Seoul. Officials investigated the incident as a mass murder-suicide, and also looked into whether Yoo had any connection to the event, but determined he wasn't involved.
Yoo is also known to have an artistic alter ego -- Ahae -- a photographer who has won international acclaim. His website appears to show Yoo taking pictures, but his face is not visible. According the website bio, Ahae was born in 1941 in Japan, where his family was during Japanese colonial rule of Korea.
On April 25, a lengthy statement from his representative was released sending condolences to the victims of the Sewol accident and condemning what it called an "undeserved attack against AHAE, his character and his credentials as an artist."
Meanwhile, off the southwestern coast of Korea, search operations continue around the sunken ferry as 16 people remain missing.
Journalist Francesca Humi contributed to this report from Paris.