A man sentenced to life in prison for murdering opposition lawmaker Koki Ishii has filed an appeal with to the Supreme Court, his lawyer said Monday.

Last week, the Tokyo High Court upheld a district court's June 2004 life sentence for Hakusui Ito, 51, for murdering the lawmaker.

Ito, described as a "rightwing activist" in court, fatally stabbed Ishii, 61, a House of Representatives member of the Democratic Party of Japan, on Oct. 25, 2002, in front of the victim's Russian-born wife, Natasha, when the lawmaker was getting into his official car.