A man surnamed Kim, 36, was Kang’s best friend from their first year of high school. They both went on to major in education at the same state university on Jeju Island. When asked how close he was to the victim, he said he knew Kang and his family “down to exactly how many spoons and chopsticks are in the Kangs’ cupboard,” in a phone call with The Korea Herald on Thursday.

He has also known Koh for a long time, since she and Kang started dating when the two were 26. “We went backpacking together once to Japan for about two weeks, Koh, my friend (Kang) and I,” he said. “They met through a community service club, of which I was also a member.”

“Koh was not a psychopath, from what I’ve seen,” he said. “If she was, they would never have gotten married, obviously. As a girlfriend, I would even say she was sweet and affectionate, just like any other normal girlfriend.”

Kim said news of their divorce came as a shock. “Honestly, I never imagined it.”

“Kang told me there were times when Koh would get aggressive, even in front of the kid,” he said. “But then he never liked discussing bad things about her because she was his son’s mother.”

Kang’s younger brother, who has known Koh since her college years, said he “didn’t know her true face” until she started “showing her ugly side” over the course of their divorce proceedings. He shared this story during an interview with The Korea Herald at his family residence in Jeju City on Monday.

“One time, my mother came to the court to plead with Koh to let us see the child, and it was shocking how she behaved,” he said. “She saw my brother with our mother and said, ‘You came with mommy? Aw.’”

Kang’s brother said Koh was “a habitual liar.” “We thought she was raising the kid all this time. But she had sent him to her parents, while not allowing my brother access to him all along,” he said.

The Kangs and Kohs previously had an amicable history. Kang, who had a passion for writing, helped the children in both families win writing contests, according to Kim.

The Kang brothers and Koh together won a government award in an islandwide screenwriting contest in 2009. Kang also penned a screenplay that won Koh, her brother and himself a prize from a state-run culture foundation in 2012.

A man surnamed Yang, 38, worked with Koh on business concerning her father’s car rental service three years ago. He said, “She was completely capable of social interactions as far as professional responsibilities are concerned.”

Criminal psychologist Lee Su-jeong told The Korea Herald that what has been perceived as Koh’s deceptiveness could be characteristic of borderline personality disorder.

But Koh is not a psychopath, according to her opinion.

“Emotional instability is something not seen in psychopaths. Borderline personalities lack self-esteem, and often display impulsive, self-destructive tendencies toward ones they have romantic relationships with -- in Koh’s case, her former husband.”

By Kim Arin (arin@heraldcorp.com)