South Korean prosecutors offered a cash reward of almost US$50,000 (S$62,590) on Thursday for information on a fugitive billionaire wanted in a probe into last month's ferry disaster that killed hundreds.
It came a day after prosecutors raided a religious compound where they believed Yoo Byung-Eun - the reclusive patriarch of the family that owns ferry operator Chonghaejin Marine - was hiding, but failed to find him.
They suspect that Yoo, 73, is responsible for unsafe business practices which contributed to the ferry's sinking last month, including overloading the ship and remodelling it to squeeze in more passengers and cargo.
"A cash reward will be provided to those reporting him to authorities," an official at the prosecutors office in Incheon told AFP.
The office confirmed reports that anyone reporting Yoo to authorities could claim a cash reward of 50 million won. Prosecutors have also asked police to put Yoo and his eldest son, Yoo Dae-Gyun, on the country's "most wanted" list from Thursday.
The billonaire's son is also being sought for questioning after ignoring an official summons.
"The father and the son are criminals who are on the most wanted list," senior prosecutor Kim Hoe-Jong said at an official briefing, according to Yonhap news agency.
"The prosecution will deal sternly with anyone who helps the Yoo family in the future course of the investigation," Kim said.
The 6,825-tonne Sewol was carrying 476 people when it capsized and sank on April 16. As of Thursday, 288 people are confirmed dead, with 16 still unaccounted for.
Hundreds of followers had been holed up in a church complex in Anseong, south of Seoul, before investigators raided it Wednesday, believing Yoo may be hiding out there.
The Evangelical Baptist Church of Korea, a splinter church group founded by one of Yoo's relatives, claimed it had no connection with Yoo, but former followers who have left the institution described him as its leader.
Police had hoped to detain him for questioning over role in the company, as well as suspected tax evasion and embezzlement, but his whereabouts are still unknown.
Yoo has no direct stake in Chonghaejin, but his children and close aides control it through a complex web of holding companies.
Yoo, who has described himself as an artist and photographer, has a colourful and chequered past. He was once convicted of fraud when a company under his control went bankrupt.
The Sewol's captain and three crew members were charged last week with manslaughter through gross negligence.
Five Chonghaejin officials have already been arrested for possible criminal negligence.