A 53-year-old man accused of murdering his 14-year-old son expressed regret Tuesday that he failed to change his son's "violent" behavior instead of accepting it as self-expression.

"I knew (my son) was suffering, and so I accepted his violence to take in his inner pain ... but that resulted in making violence a way of expression for him," said Takeki Kagawa during his trial at the Tokyo District Court. Kagawa said he should have showed his son different ways of expressing his feelings.

Kagawa is charged with beating his son Michihiko to death in his sleep in November last year after reportedly tolerating his domestic violence for nearly two years. He said that accepting Michihiko's beatings over a such a long period of time caused his, as well as his son's, ethics to diminish, reducing their consideration of each other to mere objects instead of human beings.

According to Kagawa's testimony, Michihiko began beating his parents in November 1994 a few months after he entered junior high school. As he began treating his parents like servants -- ordering them to record video tapes and go shopping -- his violence continued, Kagawa said. "To leave him alone was probably the right thing to do, but I could not do so because although he became violent sometimes, he was a good, cute boy," Kagawa said tearfully as he displayed a family photograph taken on a trip to Kurashiki, Okayama Prefecture, in August last year.

Kagawa, who plead guilty in February to one charge of murder, said he would not request a reduction in punishment or stay of execution. "I deeply thank my wife and daughter, who continue to support me even after I took their precious family member away," he said. "I must take responsibility for my mistake as long as I live."