Investigators believe they are narrowing in on the real owner of the sunken Sewol-ho ferry,
which they believe is the key to unlocking what may have caused the accident.
Key figures associated with Chonghaejin Marine Company, the practical owner of the ferry, have not been cooperating with the investigation.
Prosecutors summoned Yoo Dae-gyun, the first son of Chonghaejin owner Yoo Byung-eun, in for questioning Monday morning, but he failed to appear.
If he had shown up, they would have asked him about his involvement in Semo Group, under which Chonghaejin operates.
The prosecution is currently reviewing to issue an arrest warrant for Yoo to force him in.
Yoo currently holds majority shares in three Semo Group affiliates.
He was paid nearly 10-thousand U.S. dollars a month for his duties, and the prosecution suspects he is deeply involved with the day-to-day operations.
Investigators are also looking at him on charges of tax evasion.
Prosecutors did have a chance to talk with another member of the Yoo family on Sunday.
Yoo Byung-il, the older brother of Chonghaejin owner Yoo Byung-eun, was questioned overnight on his possible involvement in the construction of the Sewol-ho ferry and the business operations of Chonghaejin Marine Company.
Yoo Byung-eun is likely to be summoned sometime this week.
While investigators hone in on the ferry operator and owner, the search for those still missing in the accident continues off Jindo island in southwestern Korea.
Fast tidal currents have halted operations since early Saturday morning.
When divers are able to re-enter the water, they'll attempt to gain better access into fourth level of the ship, where more bodies are expected to be found.
Connie Kim, Arirang News.