The Supreme Court on Monday turned down the death sentence appeal of a 50-year-old man convicted in the slayings of seven people in Kitakyushu, clearing the verdict for finalization.
Lower court decisions said Futoshi Matsunaga and his common-law wife Junko Ogata conspired to murder six people, including five of Ogata's relatives, between February 1996 and June 1998, when the couple shared a condominium unit with them. The couple were also held responsible for torturing Ogata's father to death.
Monday's ruling said Matsunaga bears grave criminal responsibility because he was a main culprit in the deaths.
"Although he implemented two of the murders, he took advantage of his psychological control on these people for leading the remaining murders," the ruling said. "The court has no choice but to endorse capital punishment."
Ogata, 49, is still on trial at the Supreme Court because prosecutors appealed the Fukuoka High Court's decision to reduce her sentence from capital punishment to life in prison.