Yang Hoi-jeong, the former regular chauffeur of the deceased Yoo Byung-eun, surrendered to the prosecution Tuesday.
His surrender came a day after his wife Yoo Hee-ja, 52, and Yoo Byung-eun's former female aide Kim Myung-sook, 59, turned themselves in to law enforcement authorities.
Yang, 55, had been hiding out in Anseong, Gyeonggi Province, according to the Incheon District Prosecutors' Office.
The prosecution has clarified its stance that it would probe Yang and the two female aides, who have surrendered, "without detention."
The three figures were suspected of masterminding the escape of the late ferry tycoon Yoo, who was found dead on June 12. He had been on the most wanted list after the April 16 Sewol sinking disaster.