Police official Jung Yo-il said Tuesday that the student hanged himself. The boy's mother, whom local media reports say was 43 years old, had been strangled in their home in the southeastern port city of Busan. She was found by her 12-year-old daughter.
Jung said the fight started Monday night after the mother scolded her son for playing computer games.
He said the student's younger sister reported her brother had been playing violent Internet games for the past two to three years.
The Korea Herald reports that, according to the teen's sister, her mother and brother often argued over his gaming addiction, and they had fought late Monday night.
"I thought they were fighting like they normally do and just went to sleep. When I woke up in the morning, my mother was lying dead on the bed," she told the Herald.
Police officials told the Herald a note was found reading: "I was scolded for game playing and did what I shouldn't have done to my mother. I am sorry."
South Korea estimates some 2 million people are Internet addicts. The country is considered one of the world's most technologically wired, with more than 90 percent of homes having broadband Internet access.