Investigators told the Chosun Ilbo newspaper the Super Junior singer's grandparents appeared to be strangled and were found lying down in their bedroom where Teuk's father was hanging with a rope around his neck.
"We believe Lee Teuk's father strangled his parents to death and then took his own life," a police spokesman said.
Chosun Ilbo said Lee Teuk's father had been caring for his parents, who suffered from dementia, for 15 years and apparently decided to end their suffering.
The names and ages of the dead were not reported.
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