A son of the fishery official killed by North Korea at sea last month doubted the South Korean government's announcement that his father sought defection and pleaded with the president to find the truth about his father's death.

In a letter released late Monday by Lee Rae-jin, the official's older brother, the son asked President Moon Jae-in, "Do you think it really makes sense that my father, who never learned how to swim and weighed only 68 kg for his height of 180 cm, swam 38 km against the tidal current?"

He also rejected the possibility that the fishery official tried to run away to North Korea by jumping off the government ship monitoring fishing boats. His "diligent" father "was so proud of his job that he talked in my school's session to introduce his job," the 17-year-old son wrote. And even though the nature of his job only allowed him to come home twice a month, his father was a family man who adored his two children, he added.

South Korea's military and Coast Guard concluded that the 47-year-old official was shot dead by the North Korean military in waters around Yeonpyeong Island on Sept. 22, while he was trying to defect to the North. The island is located near the Northern Limit Line (NLL), the de facto inter-Korean sea border.

The son also argued that it was natural that the North knew his father's personal details, like name and hometown, only because the North must have asked those questions "at gunpoint" when approaching the man floating at sea. The South Korean government cited the North's knowing such details as evidence for the official's voluntary defection.

"My family can't believe what the government said, because they were only words and we saw no evidence (to support that my father tried to defect)," he wrote. "I still can't even acknowledge that the man found in the North's waters was my father."

"Imagine that the pains my family is going through were those of your children or grandchildren. Would you still act as you do now?" he asked. "Whose fault is this that we can't even find his body. I want to ask what the country was doing while my father was brutally murdered, and why the country could not protect him." (Yonhap)