Tetsuo Odajima, 63, pleaded guilty Tuesday in Chiba District Court to killing the wife and daughter of a former Mabuchi Motor Co. chairman and two other people in three robbery-murder cases in 2002.
Sources said Odajima's legal team narrowed down their argument to three points in the pretrial procedure. One of their points in the trial will be the constitutionality of the death penalty.
According to the indictment, Odajima conspired with Katsumi Morita, 55, who pleaded guilty in February in his trial in the Tokyo District Court, to break into the home of Mabuchi Motor President Takaichi Mabuchi, 73, in Matsudo, Chiba Prefecture, in 2002.
The pair allegedly took several hundred thousand yen and 9.7 million yen in valuables, before strangling Mabuchi's wife, Etsuko, 66, and daughter, Yuka, 40, and setting fire to the house.
Odajima is also being tried for killing a 71-year-old dentist in Meguro Ward, Tokyo, in September 2002, and his 65-year-old wife a month later.